Fixing small issues
Fixed hemisperic
Merge remote-tracking branch 'remotes/BabylonJS/master' into ScreenShotFeatureTS

Conflicts:
	Babylon/Tools/babylon.tools.js
	Babylon/Tools/babylon.tools.ts
	Babylon/babylon.engine.js
	Babylon/babylon.engine.ts
Adding some comments to explain how things work.
Rename size.zoom to size.precision (more explicit).