Added a new exception type for errors happened during file parsing.

Refs #7772
Added a publicly available function to parse a numeric range.

This is quite a useful one, as I've seen at least 3 different implementations
of that. Rigorous tests for it were added as well.

Refs #7772
Added a class to parse Map grouping files and used it in the algorithm.

Refs #7772
Added tests for Map files.

Refs #7772
Make FilePropertyWidget use default extension.

Before these changes it was using default extension for save dialogs only.
The point here is that code for save and load dialogs is doing almost the
same thing and should probably be moved to a single method. Additionally,
for some reason load dialogs are using ".ext (*.ext)" approach, while
save dialogs are displaying "*.ext" straight away. Somebody should probably
take a look at that as a maintenance.

Refs #7772
Merge remote-tracking branch 'origin/master' into feature/7772_load_map_grouping_file

Conflicts:
	Code/Mantid/Framework/DataHandling/src/LoadDetectorsGroupingFile.cpp
	Code/Mantid/Framework/DataHandling/test/LoadDetectorsGroupingFileTest.h
Fix build errors due to using initialization lists.

Refs #7772
Merge remote-tracking branch 'origin/feature/7772_load_map_grouping_file'