Fix rect drawing width & height

[ImpulseAdventure]

Scope of change

• Fix: drawRect(), fillRect()
• Reason: Existing implementation overdraws width and height by 1 pixel

Limitations of change

• Like the original code, no additional bounds checking was added (eg. if users provides zero width or height)

[ladyada]

@makermelissa heya wanna take a look? :)