Don't use WebGL if there is a major performance caveat
Improve type checking in WebGL support test
Merge pull request #1330 from twpayne/fail-if-major-performance-caveat

Don't use WebGL if there as a major performance caveat
Add ol.structs.RBush#isEmpty
Merge pull request #1331 from twpayne/rbush-is-empty

Add ol.structs.RBush#isEmpty
Add ol.Object#getProperties
Don't build ol.css in check target
Export ol.Object#getProperties
Merge pull request #1334 from twpayne/build-check

Don't build ol.css in check target
Merge pull request #1333 from twpayne/object-get-properties

Add ol.Object#getProperties
Add ol.Observable for on, once, un, and unByKey methods
ol.Object extends ol.Observable
Merge pull request #1297 from tschaub/observable

Create ol.Observable.
Fix a typo - it's writers, not witers
Merge pull request #1336 from ahocevar/fix-writers-typo

Fix a typo - it's writers, not witers