Add touch screen support

[mkerley]

Many new J2ME devices have touch screens instead of buttons or joysticks. I found an article that mentions a few methods in the Canvas class which should be helpful:

• pointerDragged
• pointerPressed
• pointerReleased
• hasPointerEvents
• hasPointerMotionEvents

Keep in mind that the average human finger (or stylus) is not accurate down to single pixels, so we may want to enforce a minimum zoom level on touch screen devices. This will keep the individual pipe segments large enough to be touched accurately.

Also, there must be some way to scroll the game screen around when it's zoomed in. I recommend a simple drag gesture (think Pipes iPhone or Google Maps).