LilyPond 2.13.28 released

[Graham Percival]

We are happy to announce the release of LilyPond 2.13.28. This release
contains the usual number of bugfixes. However, a number of critical
issues still remain, so this release is intended for developers only.

This release includes some major untested changes to the windows
lilypad editor. Windows users should not be using this release because
it is intended for developers only, but you ignore these warnings and
try it anyway, use extra caution.

Cheers,
- Graham