Fix compiling error of deprecated template.
vtkRegressionTestImage.h causes missing header compiler error with VS2012 vtk6 without test build turned on. It is not used at all, so just remove it.
Add: processing of alpha channel in color handlers
Fix: issue in ISSKeypoint3D where PointOutT is assumed to be PointInT
added references for normal estimation using integral images
Merge pull request #308 from nizar-sallem/fix_iss

Fix: issue in ISSKeypoint3D where PointOutT is assumed to be PointInT
Merge pull request #309 from holzers/master

added references for normal estimation using integral images
Update: since we can handle transparency, set alpha to 255 by default
Merge pull request #305 from yangyanli/remove_unused_header

Removing unused vtkRegressionTestImage.h
Merge pull request #304 from yangyanli/fix_deprecated_vs2012

Fix compiling error of deprecated template.
Merge pull request #306 from nizar-sallem/alpha_color_handler

Add: processing of alpha channel in color handlers