Changes:

UI:
-Made the health bar in PlayerUI visible.

Code Cleanup:
-Made and fleshed out the Unit class. Many of the methods and fields
previously in Wizard are now in Unit.

-"Made" two interfaces, one called Attack and the other called Cast.
Spellcasting units will implement Cast, physical attacker units will
implement Attack, and a hybrid unit of both will implement both.

-Other things that I can't remember, lol.

Will work on:
-Menu (difficulty setting for the computer)
-Fully fleshing out the Casting interface.
-Add frostbolt image to the Skill bar (located at bottom of screen).
Clicking on the image in the skill bar will perform the same function
as hitting the spacebar (i.e. it will shoot a frostbolt).