Shift+Smiley key will register newline character of textMultiLine

This change also
 * Honors the custom action label in EditorInfo.actionLabel.
 * Invokes InputConnection.performeEditorAction if action is specifed
   at EditorInfo.imeOptions or actionLabel/actionId.
 * Stops using InputMethodService.sendKeyChar. Implements
   sendKeyCodePoint instead.

Bug: 2498607
Bug: 5961809
Bug: 5368408
Change-Id: If4cd5eb3dacfc6b6a7ea434b0617c2438e06e42d