Remove incorrect assert, thanks @elemoine
Merge pull request #513 from twpayne/fix-tilequeue-assert

Remove incorrect assert, thanks @elemoine
Remove stray comment
Merge pull request #514 from twpayne/remove-stray-comment

Remove stray comment
Add ol.tilegrid.TileGrid.getTileCoordChildTileRange
Use high resolution tiles in WebGL renderer
Use high resolution tiles in Canvas renderer
Use high resolution tiles in DOM renderer
Store maxZoom in ol.tilegrid.XYZ
Add optimized version of getTileCoordChildTileRange for ol.tilegrid.XYZ
Remove preload from examples that don't need it
Propagate return value