Added OpenCV 3.0 compatibility to the examples with an if/else in CMakeLists

imread has moved from highgui to the imgcodecs module in version 3.0.

imread has moved from highgui to the imgcodecs module in version 3.0.

Set version to 0.

To facilitate this, added a get_texture_coordinates() method to MorphableModel

Clarified installation instructions for the header include paths

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

Also updated the documentation of Mesh.

Additionally: Using '//' for the forward declarations so they don't get picked up by doxygen

This makes all free functions show up in the generated documentation.

- We now use the same values and formulas as in Smith & Aldrian for the detector 2D variance.
- This changes the ranges of values a bit, so set an equivalent reasonable regularisation default value

Changed the detector variance in the shape fitting from clip-coords to image-coords. This makes the regularisation behave normal again.

Also chose a slightly higher regularisation value to stay a bit closer to the mean face by default.

Added an extract_texture overload that works without supplying a depthbuffer - it should be the default function to use.

- removed a few unnecessary temporary objects
- unnecessary copy-construction of objects
- formatting cleanup (whitespaces)

In the default setting, it links to OpenCV's debug libs, and that doesn't work with the STL of the RelWithDebInfo build.

This increases the readability of extract_texture a lot.