Clip singleTile image to maxExtent
Override getImageSize function to take clipped images into account

singleTile layers may have clipped images to not exceed the maxExtent.
Whitespace fixes
Use correct getImageSize API

Without the bounds argument, getImageSize would fail in singleTile mode.
Updating tests and adding a test to make sure that clipping works
Merge pull request #1036 from ahocevar/singletile-maxextent

singleTile overlays repeating when base layer has wrapDateLine false. r=@bartvde