Pictures in the docs and website

[Phil Holmes]

We have a number of pictures that are used to make the docs and the website 
clearer to understand - not the snippets, but other illustrative stuff, 
like:

http://lilypond.org/doc/v2.17/Documentation/pictures/architecture-diagram.png
http://lilypond.org/website/pictures/flat-design.png

These are placed on the website by 2 mechanisms - the website build running 
on the webserver, and the GUB docs build running on my build machine.  The 
source for both build is different.  The docs build comes from the lilypond 
git repo, where the pictures are stored as binary files.  The website build 
relies on an environment variable, $LILYPOND_WEB_MEDIA_GIT, which should 
point to another local copy of a different git repo. 
http://lilypond.org/doc/v2.17/Documentation/contributor/other-repositories 
gives details.  So we have 2 "master" copies of the pictures (and also other 
stuff, like the PDFs).

My suggestion is that we should treat the LilyPond repo as the master, and 
document a process whereby anyone editing one of the pictures, or adding a 
similar binary file, should push it first to the main repo, and then repeat 
this push to https://github.com/gperciva/lilypond-extra.

Unless something of this sort happens, the web and the docs are not 
guaranteed to be in step.

Thoughts?

--
Phil Holmes