COMP: VectorIndexSelectionCastImageFilter extra itk namespace.

The itk:: namespace specification should not be given within
namespace itk{ } -- it is against ITK style and confuses some
compilers.

Change-Id: If8b93aa0cf30aa0fd0dcddc75f1453fa667230de
BUG: ExternalData: Collapse ../ components in DATA{} paths

Relative path components need to be normalized out even if they appear
in the middle of a caller-supplied string.

Change-Id: I849b8af682053a5fa4a4e604247db2d90f8126c7
Merge branch 'BaditkNamespaceSpecification' into release
Merge branch 'release'
Merge topic 'generalize-ExternalData'

31752a3 BUG: ExternalData: Collapse ../ components in DATA{} paths