add prototype for callbackIsFinish

This commit gets rid of the following compiler warning:

lib/includes/Py_lib/libInterface.h:33:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
Remove unused variable

This commit gets rid of the following compiler warning:

lib/libNeedleman/Py_lib/libScoreComputation.c:63:13: warning: unused variable ‘j’ [-Wunused-variable]
include Python.h before any standard headers

From Python/C API Reference manual:

   "Since Python may define some pre-processor definitions which
    affect the standard headers on some systems, you must include
    Python.h before any standard headers are included.

  -- http://docs.python.org/2/c-api/intro.html#includes

This commit also gets rid of the following compiler warnings:

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/interface/Py_lib/libInterface.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libNeedleman.h:35,

                 from lib/libNeedleman/Py_lib/libNeedleman.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/includes/Needleman.h:38,

                 from lib/libNeedleman/Needleman.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/includes/scoreComputation.h:37,

                 from lib/libNeedleman/scoreComputation.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/includes/scoreComputation.h:37,

                 from lib/libNeedleman/scoreComputation.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libScoreComputation.h:36,

                 from lib/libNeedleman/Py_lib/libScoreComputation.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/includes/Needleman.h:38,

                 from lib/libNeedleman/Needleman.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/interface/Py_lib/libInterface.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]

In file included from /usr/include/python2.7/Python.h:8:0,

                 from lib/includes/Py_lib/commonPythonLib.h:33,

                 from lib/includes/Py_lib/libInterface.h:30,

                 from lib/interface/Py_lib/libInterface.c:34:

/usr/include/python2.7/pyconfig.h:1161:0: warning: "_POSIX_C_SOURCE" redefined [enabled by default]
return NULL instead of -1

The caller tests for NULL and the type of the function is "char*" so
-1 is clearly wrong.