Potentialy faster array allocation in rbush
Faster vector source clear

Three seconds speed up for clearing 100'000 features.
Introduce clear event on vector source

Three seconds speed up when clearing 100'000 features.
Clearing is now around 350ms.
Added ol.source.TileUTFGrid
Incomplete getFeatureInfo implementation
Added UTFGridJSON to the TileJSON externs
Implementation of the ol.source.TileUTFGridTile_#getData method
The preemptive loading of UTFGrid tiles is now optional
getTemplate method to get the Mustache template from the TileJSON
Added TileUTFGrid example
Add optional fast parameter for clearing vector source
Suppress warning about dot notation (compiler would report undefined properties)
Various code style fixes
Documentation blocks for the option members
Improved TileUTFGrid example
Listen 'mousemove' and 'click' rather than 'pointermove' in the TileUTFGrid example
More properties made private
Use null instead of undefined in the callback
Use writeFeatures instead of writeFeaturesNode in GPX and KML example
Merge pull request #3017 from bartvde/format-write-string-example

Use writeFeatures instead of writeFeaturesNode in GPX and KML example (r=@elemoine)