[release] bump version to 12.3
[darwin] - move isMavericks helper to DarwinUtils
[osx/mavericks] - on mavericks don't use pbo rendering with intel gpus as it might result in distorted rendering (ripple)
Merge pull request #3820 from Memphiz/Frodo

[osx/mavericks] fix rippled rendering with intel gpu
Merge pull request #3821 from MartijnKaijser/12.3

[release] bump version to 12.3