core.dot_mm: implement the 9-way dispatching infrastructure in Cython rather than C++
core.dot_mm: upgrade to 27-way dispatching (still in Cython)
all: use fancy C++ dispatching code to add optimized code-paths for C- and F-contig arrays

...for all functions.
Clean-up, document and test dispatching code
Merge branch 'ridiculous-dispatch'

* ridiculous-dispatch:
  Clean-up, document and test dispatching code
  all: use fancy C++ dispatching code to add optimized code-paths for C- and F-contig arrays
  core.dot_mm: upgrade to 27-way dispatching (still in Cython)
  core.dot_mm: implement the 9-way dispatching infrastructure in Cython rather than C++