projectlayer doesn't require an online printer; fixed display of calibrate, first layer and boundary box when updating offset.

Ability to show a calibration grid (150mmx150mm) and modify the scale, size and offset to calibrate the projected image.

Tested on both wx2.9 and wx2.8, shouldn't bring any regression.

Should remove the need for workarounds such as
http://t00tiereprap.wordpress.com/2013/04/02/messy-custom-button-placement-in-pronterface/