intermediate commit trying to fix rotate-strings-90-degrees
better fixes rotate-strings-90-degrees
Close to fixed rotate-90-degrees
rotate-90-degrees seems to work now.
print-matrix-with-labels uses new rotate-strings-90-degrees.

However, this only works correctly if all matrix elements have only
a single decimal digit.
Renamed rotate-strings-90-degrees to format-top-labels.
Make format-mat-with-row-labels adjust to max numwidth: initial attempt.

Doesn't work.