Emoji Support for all user input

All text that can be generated by users will show emoji from the shipped sprites by using the EmojiTextView instead of the normal TextView.

For all messages and posts, the custom emoji keyboard is now available as well. For this, a new LargeTextInputView has been introduced that is a sub-class of TextInputView. In order for the emoticon keyboard to work properly the existing views had to be modified heavily, sometimes resulting in new behavior such as scroll views now being above the fixed input field. Actual testing on a device (preferably with a tiny screen) is recommended to make sure this still works as expected. Screenshots will be included at the end of this post.

This MR also disables menu actions rather than hiding them and it includes a fix for a regression that was not showing the keyboard automatically in forums.

Closes #92 (closed)