ANDROID: Joystick movement and swipes
ANDROID: Support swipe-based virtcontrols

Touching and holding the left side of the screen functions as a
joystick.
Swiping the middle side allows fine control over arrow keys (eg.
dialogues), tapping it sends an enter key.
Swiping the right side up/down sends pageup/pagedown.
ANDROID: Move event types to separate file
ANDROID: Refactor touch controls to separate class
ANDROID: Access extra verbs by swiping from right