Overlays performance optimization. See #359
Update overlays unit tests.
Merge branch 'master' of https://github.com/openseadragon/openseadragon into optimization
Remove duplicate method
Merge pull request #365 from avandecreme/optimization

Overlays performance optimization. See #359
Changelog for #365
Merge remote-tracking branch 'origin/master' into Pointer-Event-Model