Deleted icons from interface, added new group for Squared Difference Module
Added new parameters to node:
1. SqaredDiffNodeID for SquaredDifference volume
2. MeanValue for mean value of SquaredDifference volume
3. STDValue for standard deviation value of SquaredDifference volume
Made some adjusment to interface. Its minimalistic now.
Changed short values to int and added filter->Update()
Merge branch 'master' into STD

Conflicts:
	RegistrationQualityModule/Logic/vtkMRMLRegistrationQualityNode.h
	RegistrationQualityModule/Resources/UI/qSlicerRegistrationQualityModule.ui