fb: add Slim'sl keyboard IME features back (1/2)

this commit adds:

- ime switcher notification - thanks cm
- slims fullscreen disable on landscape
- slims force autorotation on IME
- volume button control for navigate in the message - thanks cm
- 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: I71e93c39620cc171e658b2d7e26491bac97c651d