IOSKeyboard now can accept input from an ios UITextField control

this commit based on the PR https://github.com/xbmc/xbmc/pull/2101 which is not merged yet.
so the first 4 commits is come from that PR, the laters are the real work.

By switching to use an UITextField control, user can input any text in any native ios keyboard (original IOSKeyboard only support english and other several languages because it uses UIKeyInput protocol which has such limit), it also supports ios clipboard copy & paste.

tested on iphone4/ios 5.1.1, itouch4/ios 4.3.3, ipad/ios 4.3.3
tests on other ios platforms are welcome.