NONE Scaling Mode

[Dunnings]

Is your feature request related to a problem? Please describe.
Currently when handling canvas scaling myself, there is no clean way to disable automatic scaling by BlackEngine.

Describe the solution you'd like
Add a new ScaleMode called StageScaleMode.NONE. This would perform no action in the refresh function here:

Black/src/display/Stage.js

Line 133 in af2ae79

if (this.mScaleMode === StageScaleMode.FIXED) {

Describe alternatives you've considered
The only alternative atm is to set the scale mode to something not supported and live with the constant console error messages.

engine.stage.scaleMode = 'NONE';

[Dunnings]

Also here the canvas is always being resized to fill the window..

Black/src/drivers/canvas/CanvasDriver.js

Line 190 in 3b31e2a

__onResize(msg, rect) {

which seems like a waste of rendering to me.