Create simple UI for Abilities

Each ability equipped by the player should have a simple icon indicating the following:
* Ability has an icon to indicate which ability is equipped
* Ability has a color to indicate what type of ability (DoT, Effect [root/snare/etc], Heal, Buff)
* Ability has a 'cooldown state' when it cannot be used
* Ability has a cooldown timer showing how long until it can be used
* Ability has a hotkey to show what key to press to use it

Bonus bugfix: Accidentally stuck a bugfix for the player walking through walls in this branch too :)