ENH: np.dot: better "matrices not aligned" message
ENH: include shapes in "matrices not aligned" msg

I had to move convert_shape_to_string to common.h so that _dotblas.c
can access it.
Merge branch 'dot-errmsg' into pr/4969

Renamed not_aligned to dot_alignment_error.

Conflicts:
	numpy/core/src/multiarray/cblasfuncs.c
	numpy/core/src/multiarray/common.h
Merge pull request #2 from larsmans/dot-errmsg-no-dotblas

Better "matrices not aligned" message