BREAKING CHANGES: character->x and character->y now refer to position relative
to screen width and height (0.0,0.0 being top left; 1.0,1.0 being bottom right).
Use GetCharacterX and GetCharacterY to get position in pixels.
For consistency, it's also recommended to use GetCharacterAngle.
SetCharacterPosition/MoveCharacter still accept pixels.
To use relative positions, call SetCharacterPositionF/MoveCharacterF instead.
Also, DrawCharacter now casts the position to integer, effectively disabling
Allegro's subpixel precision. To disable casts, use DrawCharacterF.
