Pondings: Change LilyPond blog contact

As long as Janek is more or less offline (at least he won't regularly check
the given email account, Urs is the appropriate contact for the blog.
Pondings: Broadcast of Aurélien's Wagner arrangement

The announced reorchestration of Wagner's Ring has now been
performed, so the ponding now points to the radio broadcast.
keySignature-> keyAlterations

to avoid confusion with the grob KeySignature
Doc: custom key signature, simplify example

The whole-tone scale conceptually repeats the same pattern
in every octave.
makelsr and update-with-convert-ly
Use built-in make functions for finding absolute paths.
Leave extension in .dep under mf/ , as we have multiple rules
generating .dep files.
Issue 3924: Fix Jürgen Reuter's Email address in .mailmap file
Issue 3923: Use apply instead of eval for timestep finalizations