Trebuchet : Decouple iconMask and iconBack dependency

Allow them to function independently in the case where
an icon pack only has one of them.

Change-Id: I7b72bd689eac7e411f88cb5fbacea3604d45036b
Trebuchet: IT translations

Change-Id: Ib3d50a6f9d79849252d8b3fed7bb5413886d8b37
Trebuchet: PT-BR translations

Change-Id: I732a2b534ff71843b5d51485e4a414068999a45f
Merge "Trebuchet : Decouple iconMask and iconBack dependency" into cm-11.0
Merge remote-tracking branch 'upstream/cm-11.0' into HEAD