Log Message:
tex-babel{,-doc}: update to 3.31

3.28
- Fixes - wrong dir after math, in math inside tabular, in weak L
  inside R inside L, and in boxes inside math.

- \babelfont now takes into account \defaultfontfeatures. This
  is a potential source of backwards incompatibilities, but
  very likely the risks are very low, and it is, I think, the
  expected behavior.

3.29
 The fix for boxes inside math with bidi=basic(-r) broke AMS.
 I've removed the fix (a better one is under study)

3.30
- Fix: dir in boxes inside math (hopefully now it works).

- Option mapdigits for \babelprovide (only luatex).

3.31
- Basic support for line breaking with CJK scripts.

- layout=tabular now works with the 'array' package (and some
  others).