add some missing unit tests for rect accessors
supress key defaults only if display canvas has focus

keys like SPACE or backspace or only supressed (=do not trigger their
default browser action) if the canvas has focus. the canvas gets focus
when the user clicks on the canvas.

i thought about giving the canvas focus on load but decided against that;
game authors can force initial focus themsleves
gamejs.display.DISABLE_SMOOTHING flag

for retro, pixel graphics it is useful to disable the canvas smoothing;
passing this flag to display.setMode() will disable smoothing for
all surfaces created thereafter by gamejs.
unit test's `surfaceEqual` was completely broken

this commits semi-breaks the unit tests but in a good direction