of a "mutex" (i.e. the thing made by CreateMutex()) since a critical section does the
same thing but faster.

function objects.  In general, I noted that in most cases they are safe to use
from multiple threads so long as they are not modified.

violation of the strict aliasing rule.  This fixes a bug which caused
find_max_factor_graph_nmplp() to not work properly on some compilers.

asserts when creating a shared library for dlib.

vector_to_matrix(), pointer_to_column_vector(), and pointer_to_matrix() to
mat() (in addition to adding a few more mat() overloads for certain things).