Revert "Prevent gdcm::Reader copy"

This reverts commit a6be9e8950e04bdacd5e7c2c948e0e988fb14495.
Merge branch 'release'

Conflicts:
	Source/DataStructureAndEncodingDefinition/gdcmReader.h
Prevent gdcm::Reader copy
Prevent gdcm::Reader copy

Conflicts:
	Source/DataStructureAndEncodingDefinition/gdcmReader.h
Merge branch 'release'

Conflicts:
	Source/DataStructureAndEncodingDefinition/gdcmReader.h
Fix invalid return value
Merge branch 'release'