…tests for it

… apart from tps_coefs.

I might need the bending mat in semilmks relaxation. Here I'm just returning the pxp submat of L inverse.
In the 89 bookstein paper, I think he returns Linv*K*Linv, but I don't think that definition is used elsewhere.
Not sure.

I've really not tested things too thoroughly. For eg, not doing any checks on how the non-affine
part of the warp behaves.

…age Examples

See https://stackoverflow.com/a/38682136/3501947 or the np.matmul docs at
https://docs.scipy.org/doc/numpy/reference/generated/numpy.matmul.html

… if related)

I'm doing this to be able to use `solve` or `lstsq` next (instead of calculating the `inv`).

…ying.

I'm requiring mkl cuz the intermitten fail on travis is very likely due to something wrong with OpenBLAS.
See statsmodels/statsmodels#5396.

I'm removing py3.5 because requiring mkl in install trips up tox, (or I guess more specifically
python setup.py, and it throws a DistUtilsError about not finding numpy>=1.10.0).

Removing mkl cuz it does not seem to help with the intermittent NaN issue on travis.
Trying to just test on osx.

I think this might be better because of the problem is really only when I have 5 or more lmks,
and this way I can have more oses.

The README_for_docs also contains a contents local directive at the beginning,
as well as links for the high-level ops.