BUG: Fix alpha assignment for RGBA TIFF.

The alpha value should not be inverted.

Add additional test file baseline for regression testing.

Co-authored-by: Мар'ян Климов <nekto1989@gmail.com>
Co-authored-by: Ivan Kubarev <Ivan.Kubarev@materialise.kiev.ua>

Change-Id: Ic865abb18fe11739df0633888423a4b302efc2ec
DOC: Add more explanation about SmoothingQuadEdgeMeshFilter's usage

Change-Id: I23e501b89d96ef24fb0effe97a1c517f9b3deeed
Merge topic 'DocSmoothing'

48cade29 DOC: Add more explanation about SmoothingQuadEdgeMeshFilter's usage
Merge topic 'RGBATiff'

86f19dd7 BUG: Fix alpha assignment for RGBA TIFF.
BUG: Improve thread-safety and performance of PCAShapeSignedDistanceFunction.

m_Selectors is a smart pointer, and if manipulated by multiple threads, there
can be race conditions to set its value.  Through some refactoring, this
member variable is no longer needed and is removed.

Change-Id: I762dd7751e7ebfab39f77f11b1cd3ab653c69c04
Merge topic 'PCAShapeSignedDistanceFunction_release'

ffa8ff76 BUG: Improve thread-safety and performance of PCAShapeSignedDistanceFunction.