Support enums with kind specified for integer literals

[zbeekman]

e.g., the following code triggers processing errors:

ENUM, BIND(c)
    ENUMERATOR :: item1 = 0_integer32, item2, item3
    ENUMERATOR :: list1 = 100_integer32, list2, list3
    ! etc.
    ENUMERATOR :: fixed_item1 = 0, fixed_item2, fixed_item3
    ! FORD works with these
END ENUM

Here are the errors:

Traceback (most recent call last):
  File "/usr/local/bin/ford", line 11, in <module>
    load_entry_point('FORD==5.0.6', 'console_scripts', 'ford')()
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/__init__.py", line 357, in run
    main(proj_data,proj_docs,md)
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/__init__.py", line 310, in main
    project = ford.fortran_project.Project(proj_data)
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/fortran_project.py", line 95, in __init__
    ford.sourceform.FortranSourceFile(os.path.join(curdir,item),settings, preprocessor, ext in self.fixed_extensions))
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/sourceform.py", line 1023, in __init__
    FortranContainer.__init__(self,source,"")
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/sourceform.py", line 630, in __init__
    self.MODULE_RE.match(line),self))
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/sourceform.py", line 691, in __init__
    permission))
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/sourceform.py", line 602, in __init__
    self._cleanup()
  File "/usr/local/Cellar/ford/5.0.6/libexec/lib/python2.7/site-packages/ford/sourceform.py", line 1605, in _cleanup
    raise Exception('Non-integer assigned to enumerator.')
Exception: Non-integer assigned to enumerator.