Fixes #121

when ending the query with an EOF.

This commit reverts commit 89418d13.

The reverted commit will be applied in another branch (probably 'adql-2.1') as
it is part of the next release of ADQL-Lib.

- Now, `ADQLParserFactory.createParser(...)` should be used to create a parser
- Only the new function `LOWER` is supported for the moment
- Not yet possible to manage the optional features _(next dev to come)_
=> 1st step for ADQL-Lib v2.0

- TAP adapted so that using the last stable version of the ADQL language
  (i.e. 2.0 for the moment)
  - but not yet possible to set the ADQL version to use in the configuration
    file

This new function - ADQLParser.tryQuickFix(...) - fixes the most common issues
with ADQL queries:

- replace Unicode confusable characters by their ASCII/UTF-8 version,
- double-quote SQL reserved words/terms (e.g. `public`, `year`, `date`),
- double-quote ADQL function names used a column name/alias (e.g. `distance`,
  `min`, `avg`),
- double-quote invalid regular identifiers (e.g. `_RAJ2000`, `2mass`).

The last point is far from being perfect but should work at least for
identifiers starting with a digit or an underscore, or an identifier including
one of the following character: `?`, `!`, `$`, `@`, `#`, `{`, `}`, `[`, `]`,
`~`, `^` and '`'.

It should also been noted that double-quoting a column/table name will make it
case-sensitive. Then, it is possible that the query does not pass even after the
double-quote operation ; the case would have to be checked by the user.

Finally, there is no attempt to fix column and table names (i.e. case
sensitivity and/or typos) using tables/columns list/metadata. That could be a
possible evolution of this function or an additional feature to implement in the
parser.

reserved word is encountered instead of a column/table/schema name/alias.

On the contrary to the previous commit, this time a list of SQL reserved words
has been added into the ADQL grammar. In this way, the parser will ensure that
no word of this list is used in an ADQL query. The raised error is then enriched
of an HINT message stating that this word is part of SQL, is not supported
by ADQL and must be written between double quotes if used as an identifier.

The list of SQL reserved words comes from the ADQL-2.0 standard, after removal
of all potentially used ADQL words, in order to avoid a conflict with the
already existing tokens in the ADQL grammar.

clause SELECT.

[ADQL,TAP] Add STC-S and UDFs support in the ADQL parser. Now, it is possible to provide a list of allowed UDFs, regions and coordinate systems. The ServiceConnection of TAP is now able to provide these lists and to propagate them to the ADQLExecutor. UDFs and allowed regions are now listed automatically in the /capabilities resource of TAP. The type 'geometry' is now fully supported in ADQL. That's why the new function 'isGeometry()' has been added to all ADQLOperand extensions. Now the DBChecker is also able to check roughly types of columns and UDFs (unknown when parsing syntactically a query). The syntax of STC-S regions (expressed in the REGION function) are now checked by DBChecker. However, for the moment, geometries are not serialized in STC-S in the output....but it should be possible in some way in the next commit(s).

ADQLObject has now a new function: getPosition(). To allow it, the parser and all ADQL query tree item have been modified to define this function properly. The parser is setting this position for all parsed items. The test class/main function "TestGetPositionInAllADQLObject" aims to check that after a parsing all items really have a defined position.

ADQL: Fix an ADQL bug (raised by Dave Morris) in the management of subqueries: before, it was impossible to use (in a clause different from the FROM) columns of a father query inside a subquery.