The new pybind11 bindings require at least Eigen-3.2.7. Travis and Ubuntu 14.04 only include Eigen-3.2.2, so let's include Eigen as a submodule.
Unfortunately Eigen uses Mercurial and no official git mirror exists, so I've cloned Eigen's mercurial repo and added it at patrikhuber/eigen.git at version tag 3.3.3.

This includes their new Eigen3 bindings

The submodule is the current master, which is exactly v1.2.2.
The removed local copy is v1.1.1.

Files saved with the old version seem to be readable with the new version. (apart from the fact that we've now changed to Eigen, which makes it incompatible to the old models.)

Includes my multidim-array PR plus a fix for the overload resolution in ::to/at

This contains a NNLS solver, which we use to solve for the blendshape coefficients.

Submodule points at release tag 0.9.8.3

I think what happened earlier is by merging the old python-bindings branch first, the pybind "upgrade" was actually a downgrade. But now it should be back to the latest.

This fixes the constexpr bug with VS2015U3

* The changes were necessary to fix issues with Ceres's Jet type in glm vector and matrix types
* Added glm-git-modified-readme.txt to explain these changes

The OpenGL mathematics library (http://glm.g-truc.net/) - it'll be used for its 3D rendering related functions