Standardize python property vs function on Property class. Refs #6677

Now behaves more consistently and like the original.
wiki_maker can now work with a debug build of Mantid on Windows

Any calls to mantid are done via a subprocess but only when running in
debug so as not to compromise the speed of using it in release. Refs #6677
Merge branch 'feature/6677_wikimaker_win_debug' into develop Refs #6677

Conflicts:
	Code/Mantid/Build/wiki_maker.py