Also added a setup.cfg template to specify paths to the libraries we need (mainly useful on Windows where CMake needs the locations).
Updated .gitignore.

On Windows, it uses the "Visual Studio 14 2015 Win64" generator.

Eigen only introduced rsqrt() in 3.3. Eventually, we'll switch back to rsqrt(), or even include Eigen directly under 3rdparty/.

This allows to completely create a model in Python from numpy matrices, and store with save_model.

This was in the past used for converting a small BFM json model to a cereal binary. However, it was never satisfactory.
I think it's also used to import the blendshapes from Matlab into C++, so we'll need it again at some point. However at the moment it does not compile as we don't have a json serialize() (cereal) function for Eigen::Matrix.

For some reason, not all changes got staged in the last commit. This is the full set of changes.

Actually, we still read into an OpenCV matrix - should change that in the future to directly read into an Eigen::Matrix.

Also removed division by 1000 of the mean. I don't think it makes sense to make this modification. Leave it as it is in the original.

This is a big step towards being not requiring OpenCV anymore as a dependency.
All models will have to be converted and re-downloaded.

* PcaModel: Removed the RNG from the class, and added a RNG parameter to the draw_sample method
* PcaModel: Added a get_eigenvalues() accessor that returns all eigenvalues
* MorphableModel: Changed CEREAL_CLASS_VERSION from 0 to 1 (and added a version check to the serialize method)
* MorphableModel: Changed texture_coordinates from cv::Vec2f to array<double, 2>
* Added binary Eigen::Matrix serialisation for cereal
* Changed Blendshape to Eigen::Vector as well
* Adjusted blendshape_fitting.hpp accordingly - and it now takes most parameters by const&
* Adjusted fitting.hpp accordingly - now also takes most parameters by const&
* Adjusted linear_shape_fitting.hpp: It's not totally converted, still using cv::Mat for the core algorithm

It hasn't had a method to return a Mesh in quite a while I think.

Hopefully this is not an issue anymore.

CMake changes (built in windows and linux):
* Include newest eigen3 CMake file
* Make CMake scripts work with OpenCV 3.1

The diff looks really weird because I clang-formatted the whole document. But there should be no changes in extract_texture, except for tabs->spaces.

* Can now return any cv::Mat to Matlab
* Can convert 3 and 4-channel images from Matlab to cv::Mat

1) Fixes for OpenCV > 2.4.3
2) Update to newest eigne3 cmake file (support in environment variables).

This enables defining multiple functions per Matlab mex module

Can return 4-chan uchar matrices (isomaps) back to Matlab, and convert 3-chan uchar matrices (images) from Matlab to C++.

These are required for extract_texture in Matlab.
Maybe the better strategy would be to add a constructor to RenderingParameters and not have all these setters.

* Convert Frustum back and forth
* Convert RenderingParameters back to C++
* Convert glm::mat4x4 back to C++

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