Fix compatibility issues with Love2D 0.8.0

See:

 * http://love2d.org/wiki/love.graphics.setNewFont
 * http://love2d.org/wiki/love.graphics.newCanvas
 * http://love2d.org/wiki/love.graphics.setCanvas
 * http://love2d.org/wiki/love.event.quit
Merge pull request #1 from potomak/master

Fix compatibility issues with Love2D 0.8.0