LoadResources() for ehm loading resources added, also...

... Changed MOUSEACTION to ButtonState, it just feels more natural in my
opinion, also moved it to globals.h. Optimized graphic matching for
UI_elements. Added overload for AddButtion Menu class function, so now
we can choose at what coordinates we set the button at. Added
CharacterSelectionMenu screen, and 2 buttons, new class for player class
icons needs to be introudced here tho, as buttons already have their
graphics defined. Fixed unsigned/sigend operator mismatch warning.