LSR --safe mode

[Graham Percival]

All the snippets in input/lsr/ should (in theory) be safe, since they 
are generated from LSR, and LSR only accepts snippets if they compile in 
--safe.  Still, we should have an automatic testing before adding stuff 
to GIT, so I don't have to look at the snippets myself all the time.

I can think of two ways to do this; which is better?
1)  Run "lilypond --safe" on each file when I import them from LSR, 
before committing to git.  I would do this as part of the 
buildscripts/makelsr.py file, but I don't know how to run "lilypond 
--safe" and check that there's no errors, as part of a python script.

2)  Compile input/lsr/ with "lilypond --safe" instead of lilypond.  This 
would require modifying the "make web" buildscripts, but I'm not certain 
how I would go about this.  John?

Cheers,
- Graham