Refs #8349. Merge remote-tracking branch 'origin/master' into 8349

Conflicts:
	Code/Mantid/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/MuonAnalysis.h
	Code/Mantid/MantidQt/CustomInterfaces/src/MuonAnalysis.cpp
Refs #8349. Fixed Qt warnings.
Refs #8349. Got rid of all the wsIndex uses.

It was needed because for some reason previously workspaces with group
held the data of all the groups, not just for the one. In one of the
tickets I've fixed it so now we should always have one wsIndex only.
Refs #8349. Removed function accidentally left after merge.
Merge branch 'feature/8349_muon_plot_moving' into develop

Conflicts:
	Code/Mantid/MantidQt/CustomInterfaces/src/MuonAnalysis.cpp