Remove trailing whitespace
Only load ol.css in loader.js

Before this change, all the examples try to load ../css/ol.css, even in
hosted mode, where they should load ../build/ol.css instead.
Add pixelRatio to ol.TileUrlFunction
Add pixelRatio to ol.source.Tile#getTile
Add ol.source.Tile#getTileGridForProjection
Use ol.source.Tile#getTileGridForProjection
Add ol.source.Tile#getTilePixelSize
Add HiDPI support to ol.renderer.canvas.TileLayer
Add HiDPI support to ol.renderer.webgl.TileLayer
Add HiDPI support to ol.renderer.dom.TileLayer
Add HiDPI support to ol.source.TileWMS
Activate HiDPI support in wms-tiled example
Activate HiDPI support in wms-custom-proj example
Scale WebGL output canvas by devicePixelRatio
Move format exports into child classes.

To only export implemented methods.
Add new TopoJSON format.
Bring topojson examples back
Add TopoJSON source & use it in example
Bring tests back
Add TopoJSONOptions literals for source & format