Add gutter option to ol.source.TileWMS
Add gutter support to TileUrlFunction
Add ol.source.Tile#getGutter
Add gutter support to ol.renderer.canvas.TileLayer
 Add gutter support to ol.renderer.dom.TileLayer
Add gutter support to ol.renderer.webgl.TileLayer
Merge pull request #1350 from elemoine/gutter

Add gutter support to ol.source.TileWMS