Rework optimised pixel reading
optimizedWriteToRGBAFillA wants bitmask not half
Test optimisation

Moved test for Sampling params to SetFrameBuffer for efficiency:
enforce sampling=1

Added test for different channel patterns
Variable and tiny datawindows in optimisation test
Cleaning up the code for namespace usage
tidied up comments in new optimisation functions
Merge branch 'develop' into optimisation-bugfix

Conflicts:
	OpenEXR/IlmImf/ImfScanLineInputFile.cpp
	OpenEXR/IlmImfTest/Makefile.am
	OpenEXR/IlmImfTest/main.cpp
	OpenEXR/IlmImfTest/testOptimizedInterleavePatterns.cpp

Additional code style changes
Merge branch 'develop' into exrenvmap-cleanup
Merge branch 'exrenvmap-cleanup' into develop