lilypond 2.13.38

[Graham Percival]

Since the "spacing alist" bug seemed to be a problem for people
experimenting with the spacing stuff, I went ahead with 2.13.38 to get
that bugfix out there.

Bug squad: Phil is busy with the opening of a musical, so it would be
nice if somebody else could check the regression test comparisons for
both 2.13.37 and 2.13.38.  It would be a shame if some horrible bug
was introduced in the past two weeks and nobody noticed.

The next release will probably be labelled a "beta" test.

Cheers,
- Graham