AIFile bug fixes.

Compare with errno instead of rc.
Make sure errno is preserved.
Fix shadow dithering. It's still pretty ugly tho, but looks okay if ssao is enabled. May add random kern in the future.
AIAlert fixup.
Revert upstream change to particle index accounting. (Fixes flicker issues)
[LLScrollColumnHeader] Fix icons disappearing in certain states, such as click.
[LLScrollColumnHeader] Fix the ImageOverlay icons being overwritten every draw and thus destroying our image_overlay parameter!

Seriously, whose idea was that?
Ignore space changes and this will be a lot easier for all of us.
[Warnings] Fix signed/unsigned mismatch in llpartdata.cpp
Merge branch 'master' of git://github.com/AlericInglewood/SingularityViewer
Merge branch 'master' of git://github.com/Shyotl/SingularityViewer
Merge branch 'master' of https://github.com/singularity-viewer/SingularityViewer