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

Change CMAKE_SOURCE_DIR to CMAKE_CURRENT_SOURCE_DIR

This fixes wrong paths in case someone includes eos in CMake with `add_subdirectory`.

Matlab's default precision is double, that's why we only convert MatrixXd for now. Added a note highlighting this.

Otherwise, when another project includes eos via add_subdirectory(), these paths will refer to the top-level CMakeLists, not this one from eos.

This was omitted earlier by accident

Remove unused 'cmake_minimum_required' commands

This is more or less the coding style that should be followed for new contributions.
I am happy if code differs from this style a bit if there is a valid reason for it.

It's a rough first version of this file, it may change a bit over time, if required.

Remove unused 'project' directives

Replaced all instances of old Vertex class with Vertex<float>, so now there's only one vertex class.

Forgot to add in earlier commit - this should fix compile error.
Also added cv:: in Rasterizer to fix second compile error

- Moved divide_by_w to render_detail
- Include utils.hpp for clip_to_screen_space()

Not sure yet whether it's a good design decision!

Also if we keep it this way, have to add proper getters, make member variables private, etc.

Using the new renderer stuff.

It is modeled after the vertex shader / fragment shader approach of modern OpenGL.
It also includes a texture extraction fragment shader, which hopefully will replace the current affine texture extraction.

This is still very much experimental, containing lots of todo's. For example it contains lots of if-hacks to select the correct fragment shader (for rendering or texture extraction).

Top level CMakeLists.txt already check '3.1.3' so there is no need to check
it for subdirectories

'project' declare independent block of CMake code. If block is not designed
to be used stand-alone it make no sense to declare 'project'

Consistent 'REQUIRED' usage

Tabs to spaces in main CMakeLists file

Using 2 spaces for CMake code for now

Adjusted all includes, files and bindings.

In contrast to the MorphableModel member function draw_sample, this method takes blendshapes coefficients too and returns a full assembled mesh.