Remove unused CSS classes

The classes ol-layers, ol-layer-image, and ol-layer-tile are not used.
Strip debug classes when compiling
Re-enable logging
Log WebGL shader and program errors
Export ol.Map.updateSize
Always set CLOSURE_NO_DEPS to true
Merge pull request #672 from fredj/export-update-size

Export ol.Map.updateSize
Merge pull request #666 from twpayne/remove-unused-css-classes

Remove unused CSS classes
Merge pull request #668 from twpayne/strip-debug-classes

Strip debug classes when compiling
Merge pull request #673 from elemoine/closure-no-deps

Always set CLOSURE_NO_DEPS to true
Giving the map a getFeatureInfoForPixel method

This method is an entry point for getting feature information.
Renderers can use a hit canvas or defer to a layer (source) to
get matching features for a pixel.

For now this is only implemented for vector layers, and it uses
a bbox query because we cannot refine the result because of
missing geometry intersection functions yet.
Get hit candidates from RTree, then refine result

Now we get exact hits also for lines and polygons.