Some usability things

[p0nce]

• [x] microstudio has mouse.x instead of mouse.positionX, I like it
• [ ] double windowWidth() can only be used inside a draw override. Not fantastic with mouse events. Need a screen.width object somehow
• [x] mouse.left as an alias for button isPressed
• [x] keyboard.isPressed as an alias for keyboard.isDown
• [x] randInt strangely missing, or dice?