Use oli/x.js as input files when compiling examples
Add explanation on using externs as input
Merge pull request #2822 from gingerik/externs-as-source

Remove obsolete comment
The imageExtent option is required
If image size is not provided, determine resolution on load
Let image resolution be calculated when the image loads
Allow renderer to load the image
Clear the canvas on layer extent changes
Unregister listener
Change comments for examples_star_json build target
Merge pull request #2825 from elemoine/oli-olx

Change comments for examples_star_json build target
Merge pull request #2796 from tschaub/lazy-size

Determine image size on load.
Merge pull request #2757 from tschaub/new-extent

Clear the canvas on layer extent changes.
Add ol.geom.Polygon.fromExtent