fb: add back all keyboard IME features back (1/2)

this commit adds:

- ime switcher notification - thanks cm (NOT ADDED - ALREADY IN)
- slims fullscreen disable on landscape
- slims force autorotation on IME
- volume button control for navigate in the message - thanks cm (NOT ADDED - ALREADY IN)
- slims force to show always enter key

some fixes to the 4.2/4.3 implementations + added full multiuser
support for all this features

cheers

Change-Id: I97973c30f1f97cfa77085fe431ae96e6aab0df6b