Create new branch for GLM 3.1.0b1

[robertladwig]

I've committed the newest GLM executables for version 3.1.0b1 for Mac, Linux and Windows to the branch "GLMv.3.1.0a3". Can we copy that branch to a new name, e.g. "GLMv3.1.0b1" and delete the "GLMv.3.1.0a3"-branch to avoid confusing other users? After some testing of the new GLM-AED2 version we could eventually merge it with master later and submit it as a new release.