COMP: Fix variable type for Set/Get macros

The wrong pixel typename was used for the Set/Get methods. This causes
a conversion warning with gcc 4.1.

Change-Id: Iee7e42258e5b19c69c76b3c1cb366cbdfba064a7
DOC: Fixed HistogramThresholdImageFitler

Filter not Fitler.

Change-Id: I2178e4dcf0aba4bb012a67c15d182d4d1559ff4c
BUG: Improve SWIG version check

See ITK-3303
The swig version was checked before SWIG_VERSION was defined when using system swig.
There is now also a new variable, ITK_SWIG_VERSION, which defines ITK's swig version,
and is propagated to SWIG_VERSION when using ITK's swig.

Change-Id: Idc755567691d32543997797a7d85443a1488a3ed
Merge branch 'FixFitlerTypoForRelease' into release

Change-Id: Ibb05de6d27c6c94071d8b455b972d1eb7cc65ce3
Merge branch 'FixThresholdMaximumConnectedCompone' into release

Change-Id: I9104c6bad3f7fe319c3a644b120336912919a7b3
BUG: Add VTK_VERSION for older VTK versions

For older VTK's, VTK_VERSION is not defined. It needs to be setup manually.

See ITK-3304

Change-Id: I5efec656190e7417c7a2cbfa1b27b8b545261ca0