Add ol.source.ImageWMS#setUrl
Make ol.extent.buffer return an extent instead of mutating
Add ol.source.wms.DEFAULT_VERSION
Factor out WMS version 1.3 check
Refactor ol.source.TileWMS URL logic
Remove unused ol.source.wms.getUrl function
Remove unused ol.TileUrlFunction.createFromParamsFunction
Correct ol.renderer.canvas.ImageLayer transform for HiDPI devices