Fix android::base::utf8Decode()

There was a bug in the case where the input buffer is larger than
the UTF-8 code point, and this case was not tested properly.

Change-Id: Ifd6a1b455f3167e09835dffb624db86f4bbed936
android/skin/event.h: Add kEventTextInput event.

To better match the SDL2 input event model, create a new event
type used to text input, as opposed to raw key presses.

Now, whenever a key is pressed, two events will be generated
with SDL1.x: One kEventKeyDown event + one kEventTextInput one
containing the corresponding Unicode value.

Change-Id: I98157c4c4075aa09a83c721ba7b4a5bbe94ef1f6
android/skin/ui.c: Add debug messages for input events.

Change-Id: I4153137253c0542b7ee84268ccf71b014dd05a5c
Merge "Fix android::base::utf8Decode()"
Merge "android/skin/event.h: Add kEventTextInput event."
Merge "android/skin/ui.c: Add debug messages for input events."