Make reference pitch for \relative non-optional

Make reference pitch for \relative non-optional

Using \relative without reference pitch has been deprecated for a long
time, so this change brings LilyPond's codebase (and files converted
using convert-ly) into conformance with recommended practices.


Obviously contains commit

Run scripts/auxiliar/update-with-convert-ly.sh

[dak, 2013-03-09 13:53:04]

Finetune conversion rules to get \relative c' or \relative do' in unambiguous
cases

[janek, 2013-03-12 22:25:42]

LGTM.

I think it would be clearer if the descrption focused more on this change, and a
bit less on explaining context of \relative discussions.

In other words, the sentence "This is intended as a potential migration strategy
to issue 3229 where
leaving off the optional reference pitch leads to a different default." is quite
difficult to understand imo.

cheers,
Janek