No more input/regression/ links in manual

[Graham Percival]

I'm currently removing all "see also" links to input/regression/*.ly 
from the docs.  These files will be categorized (or "directorized"), 
placed in LSR, and will appear in the new "Snippets" infrastructure. 
The relevant doc pages in the manual will point to the appropriate 
directory.

Please don't add any @file{...regression...} links to the manual.  If 
you have an example that has useful info, please place it in the
input/tolsr/
directory.  (ie put copies of the example in input/regression/ and 
input/tolsr/ )

I'll be creating this dir soon (once I've done an initial clean-up of 
the 48 current examples in there).  Once the initial backlog is cleared 
up, I'll process any new snippets ASAP.  (if a developer wants to add 
the snippets directly to LSR, that's quite welcome; I'm just offering 
this in case you just want to dump your regtest there and move on to 
other things)


Why this complication?  IMO, input/regression/ should be for developers 
only; it's too confusing for users to look for snippets in input/test/, 
LSR, input/regression/ (looking at 48 useful examples in the midst of 
468 developer-only tests), etc.  The fact that we have any 
@file{...regression...} links in the docs are a holdover from the Early 
Days (tm).

Cheers,
- Graham