Fixes #78
Fixes #60

This aims to prevent extending UserDefinedFunction for UDFs whose translation
is very simple (e.g. different name in SQL, different argument order, etc).

Fixes #115

`fix_on_fail` in the configuration file. By default, this feature is disabled.

_With 15cd5944, this commit finishes the resolution of the GitHub issue #104 ._

commit.

`upload_max_file_size` and `upload_default_db_limit`.

Before this fix, cancelling a TAP job (async or not) which was formatting the
result in ASCII may failed, especially for large results. This was due to a
non interruptible alignment process. This process is now checking whether a
cancellation has been requested before formatting a new result line/row ; if so,
the process is immediately stopped and the job can be cleaning declared as
aborted.

(see previous commit).

The property `upload_default_db_limit` has been deprecated. Indeed, in the
current state of the TAP protocol, this makes no sense: the user can not change
the limit size (in bytes or rows) for uploaded tables.

The property `upload_max_file_size` has been deprecated. It is actually
duplicated: `upload_max_db_limit`, if expressed in bytes already lets put a
limit on the maximum size of an uploaded table/file.

The property `upload_max_request_size` has been added. It lets set a maximum
size for a whole HTTP Multipart Request. By default it is set to 250MB.

The default value of `upload_max_db_size` is now 1 million rows.

The UPLOAD feature is still disabled by default (i.e. `upload_enabled=false`).

Then, UWS or TAP implementors are free to use whatever logging system they want
(e.g. log4j, logback, ...).

The end of the description of a UDF was not detected when this UDF was followed
by another UDF definition. This was due to an incorrect double quote escape in
the regular expression of a UDF's definition.

Although the Java code allowed the specification of a description of a User
Defined Function, it was not possible to set one in the UDFs listed in the
configuration file.

in the TAP configuration file.

This commit resolves partially the issue #28

Ideally, there should be an implementation of UWSLog and TAPLog working with
Log4j and another for SLF4J (and eventually for other logging mechanism).
Additionally, an implementation storing log messages in database would be
interesting. All these ideas may be implemented in UWSLib and TAPLib in a
future version.

On the contrary to other DBMS, MySQL supports schemas, but as databases.
Which means that JDBCConnection gets from the JDBC driver that MySQL does
not support schemas and so it tries to access TAP_SCHEMA tables with a
'TAP_SCHEMA_' prefix instead of 'TAP_SCHEMA.' one. Since MySQL does
behave like it supports schemas, JDBCConnection.supportsSchema must be
set to 'true' if the DBMS is MySQL.

Besides, since no schemas are returned by the JDBC driver
(cf DatabaseMetadata.listSchema(...)), the function
JDBCConnection.isSchemaExisting(String, DatabaseMetaData) must always assume
that the specified schema exists if the DBMS is MySQL. This is particularly
important when the existence of 'TAP_UPLOAD' must be checked, because if the
function returns 'false' the library will attempt to create the database/schema
'TAP_UPLOAD' and will obviously fail due to a lack of permissions. Of course,
it means that the TAP implementor must create manually the schema/database
'TAP_UPLOAD' him-/her-self.

The second particularity of MySQL is the quote character for identifiers.
It is a back-quote (`) instead of a double quote ("). To reflect this
difference, JDBCTranslator.appendIdentifier(...) has been overwritten in a new
JDBCTranslator extension: MySQLTranslator.

The translation of all SQL types and mathematical functions have been adapted to
MySQL according to the online documentation. Few tests have been done locally
with a tiny database. This seems to work but further testing should be
performed in order to ensure the stability of this implementation.

apply a quick space replacement (by %20) for few URIs of the configuration file
and remove duplicated entry (encoding) from the Gradle build script.

A special test has also been added in getFile(...) in order to deliver
a clear error message for users using a former version with URIs in their
configuration file (only for file_root_path and metadata_file).

Two embedded DBMS are used: H2 and a little SQLite. JDBC drivers are provided
in the `lib` directory. The databases are created and deleted automatically
by the JUnit tests (see `test/tap/db_testtools/DBTools for more details`).

The ANT and Gradle build scripts have been updated to reflect all these test
modifications.

This is very helpful if TAP_SCHEMA (or some of its tables and their columns)
has a different name in the database.
The mapping can be specified to JDBCConnection or directly in the configuration
file.

See the commit bd621842,
for the first part of the fix (which actually did not really
fixed the problem: connections "idle in transaction" were
still in the database ; the connection being inside an opened transaction,
it generates lock issues in the database in addition of probably taking
some memory resources).

The transaction and Statement were closed too early before.
  - Fetching the row was not possible once the first bunch of fetched
rows was over.
  - The problem of "statement is aborted" preventing the re-use of
a same DB connection was apparently still there, but occurred less often.

  Now, any transaction potentially started in a DB connection is always
closed after one of the public functions of JDBCConnection is called ;
except executeQuery(ADQLQuery) whose the call MUST be wrapped inside a
try...catch block in which DBConnection.cancel(true) MUST be called
in case of error (in order to effectively end any started transaction).

with a constructor having a Properties object loaded with the content
of the current configuration file.

Can be enabled just by providing a file URI in the TAP configuration file using
the property "examples". It is also possible to add manually a TAP resource
whose the returned name must be "examples" like the new TAP resource is doing:
tap.resource.Examples. This latter take a file URI as the TAP configuration
file does. The referenced file must respect the DALI 1.0 or TAP Notes 1.0
syntax. No check of the file is performed by the library ; it is up to the
author of the referenced file (a XHTML/RDFa file) to write a correct "examples"
endpoint content. Check out the examples provided on the GitHub repository in
the directory examples/tap/examples_endpoint.

1) [TAP & UWS] ]MAJOR BUG FIX: The abortion of an SQL query is now correctly
implemented. Before this fix, 2 mistakes prevented this clean abortion:
  a/ The thread was not cancelled because the SQL query execution was
blocking the thread. Then the thread could not treat the interruption though
it was flagged as interrupted.
  b/ The function UWSJob.isStopped() considered the job as stopped because
the interrupted flag was set, even though the thread was still processing
(and the database too). Because of that it returned true and the job phase
was ABORTED though the thread was still running.
  NOW:
  a/ TAPJob calls the function Statement.cancel() (if supported) in order
to cancel the SQL query execution properly inside the database.
  b/ The function UWSJob.isStopped() does not test any more the interrupted flag
and returns true only if the thread is really stopped.
  IN BRIEF: It is now sure that a job in the phase ABORTED is really stopped
(that's to say: thread stopped AND DB query execution stopped).

2) [TAP] BUG FIX: When the writing of a result is abnormaly interrupted for any
reason, the file which was being written is deleted.

by the TAP configuration file in order to add/remove/change some metadata or
to change the output of the TAP resource '/tables'.

[TAP] Fix NullPointerException in TAPConfiguration (this error happens only when a NoSuchMethodException occurs.

[TAP] Add Javadoc for all TAP configuration file related classes + Improve the function ConfigurableServiceConnection.getFile(...) + Set the default value of limits/durations/periods to the maximum value if the new maximum value is less than the current default value.

[TAP] Incorrect setting of the backup frequency. The documentation was also incomplete about this property, but also wrong concerning the property backup_mode which is actually backup_by_user.