configurable canvas dimensions

This adds the ability to specify what the size of the canvas element will be instead of being locked to 300x300. You can also now choose whether to treat the offX and offY like ints (more consistent spacing) or doubles (fills out entire canvas no matter what the size of the grid or the element).

Results from running the new constructor:
`VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'), 640, 480, true);`
![VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'), 640, 480, true)](http://i.imgur.com/TGAVvjl.png)
`VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'), 640, 480)`
![VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'), 640, 480)](http://i.imgur.com/nVbbIys.png)
`VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'))`
![VilTAGEConfig vtc = new VilTAGEConfig(querySelector('#console'))](http://i.imgur.com/qLYyA97.png)