Using nanoflann's kd-tree for fast searching

Fixed previously uninitialised screen_width/height in constructor from ScaledOrthoProjectionParameters

These changes are for the closest edge fitting.

* Function to compute the mesh contour vertices
* nanoflann adaptor for vector<Eigen::Vector2d> (it should work with glm::vec2 too actually)

clang and gcc complained about this, while VS2015 accepted it. It turns out this is the much better way to do it!

Added SOP algorithm to features, added Python bindings section, updated GLM path and added note to clone with --recursive.

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.

* Now using the transparent glm bindings
* Replaced nonlinear camera estimate with the linear algorithm
* Updated RenderingParameters bindings