tweaked CMake to search Anaconda for Python first (#324)

# Third Party Dependencies

find_package(GSL           REQUIRED)

find_package(Eigen3 3.3    REQUIRED NO_MODULE)

find_package(Python        REQUIRED COMPONENTS Development)

find_package(nlohmann_json REQUIRED)

# If there is an Anaconda environment activated, search that for Python first

if(EXISTS $ENV{CONDA_PREFIX})

  message("Searching $ENV{CONDA_PREFIX} for Python libraries")

  set(Python_ROOT_DIR $ENV{CONDA_PREFIX})

  set(Python_FIND_STRATEGY LOCATION)

endif()

find_package(Python        REQUIRED COMPONENTS Development)

# Library setup

set(ALE_BUILD_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/include/")

set(ALE_INSTALL_INCLUDE_DIR "include/ale")