Added new tests for mapping and looping.
Added equality testing for the MetaFile
Refactored this class to separate getting constraints from different sources.
Added a bit more logging and error messages to Exception class
Made this class return MetaFile rather than file name objects for consistency.
Altered use of mocks in this test
Updated this test to fit with the PatternDS MetaFile changes
Stopped git picking up my emacs autosave files.
Altered way that mapping works.