fixing collada examples on github
Fix for the removed `getNormalVector()` in CurvePath.getWrapPoints

- See #4105
Examples: Add GPGPU bird to examples index list
Examples: Refactoring gpgpu renderer based on @WestLangley suggestion #4069
Examples: tweaking gpgpu birds' shape and colors
Merge branch 'master' of https://github.com/zz85/three.js into dev
Merge branch 'fixing-collada-examples-on-github' of https://github.com/danielribeiro/three.js into dev