Merged the face camera boolean and axes parameters used by BillboardSet & Text3D into a FaceCameraMode enum. Implement none, rotate XYZ, rotate Y, lookat XYZ & lookat Y modes. More can be added as necessary.
Travis CI: API documentation update at 2014-05-12 20:18:28 UTC.
[ci package]
For Travis CI - switch CI build to use OS X build environment.