Add Hashable interface
Implement hashCode for ol.style.Circle
Add atlas manager
Double the size when creating new atlases
Add constant `ol.has.WEBGL_MAX_TEXTURE_SIZE`
Merge pull request #18 from elemoine/webgl-point-misc

[webgl-point] Misc changes
Replace hashCode with checksum

Hash codes are not collision free, so what we
actually need is a checksum.
Support image rotation
Only create new atlas after testing all existing
Use id string instead of hash code
Take `space` into account when checking size
Support image rotateWithView
Move AtlasManager to `ol.style.AtlasManager`
Add comment describing the vertices sent to GPU
Use LINEAR for icon textures
Use 30000 points in icon-sprite-webgl example
Make icon-sprite-webgl example usable with Canvas
Merge pull request #19 from elemoine/webgl-point-rotation

[webgl-point] Add support for icon rotation
Add AtlasManagerOptions and improve docs
Add feature overlay support to webgl map renderer.