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.

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

Also removed a few trailing whitespaces

For path operator +=

Removed all non-header-only CMake stuff and added a custom target for the library headers so they show up in IDEs