Re: Make #{ #} accept everything an assignment accepts. (issue 4974046)

[dak]

I have decided to be an ass and push this change.  It touches
astonishingly little code, is surprisingly useful and simplifies
extending Lilypond considerably, passes the regtests, and I like its
code.

It would be a pity not to make it available to users.  The programming
documentation, in spite of the fundamental character of the extension,
has rather limited changes in the text surrounding the new examples, so
this new last-minute job for the translators has a good payoff in value
for users.

I apologize for the indecency of flushing this change out on such short
notice, but I really think it solid, and the limited incompatibilities
it introduces (which can't be
covered by convert-ly automatically) more likely than not help the user
in writing simpler, cleaner code.

http://codereview.appspot.com/4974046/