once every few thousand iterations.

global functions.

inside mex files.  This way, if you use matrix_colmajor or fmatrix_colmajor
in a mex file it will not do any unnecessary copying or transposing.

ODR violations.

and LAPACK that comes with MATLAB since trying to use any other BLAS or LAPACK
generally makes MATLAB unstable.

doesn't have it.

CMake.

a little bit.

Drectangle equality

Only issue is that the strong is hardcoded - otherwise
this is actually technically required by PEP 396

Add a simple print and serialization scheme for
shape_predictor_training_options. This enables you to serialize
your training options.

Easy change to allow comparisons on the Python side for
both rectangle and drectangle

This is in the main dlib source code (rather than specifically
Python). Equality operators were missing for drectangles and
so were copied from rectangle.