Reorganize trac instances location

[strk]

In order to clearly separate app data from statically served files it will be useful to have 2 directories under /var/www/trac, one named "instance" with all the instances and one named "htdocs" or "html" with the static files.

Until recently /var/www/trac was the DocumentRoot for trac.osgeo.org and this opened up access to a lot of not-intended-for-public-eyes files.

Now the DocumentRoot for static files was moved (by myself) to /osgeo/trac/htdocs, while /var/www/trac remained for the instances.

I hadn't moved the instances because I was concerned about the backup procedure, which (I've been told from Martin) uses trac-admin and references instances via "/var/www/trac/<instancename>"

[strk]

For the record, the current DocumentRoot is back under /var/www/trac/html - instances are not moved one directory down yet, but would still be nice to do that. Backup scripts are under /osgeo/ and there are also other scripts in use expecting instances to be under /var/www/trac. Hopefully all under /osgeo/tools

[strk]

I've just read that in order to switch to WSGI setup (could make trac faster) we also need all instances (environments) to be under a directory containing nothing else. See ​https://trac.edgewall.org/wiki/TracModWSGI#Thetrac.wsgiscript

I suspect having more directories (like we have now) also affect performance of the mod_python version of the deploy (as it is now).

[strk]

Scripts all updated, and symlinks removed. Considering this done. File new tickets shall any issue arise.

[martinl]

See #1872

[strk]

SVN hook scripts also had the old path, I've now updated them.

Doing the changes I noted some hook scripts that are likely broken (and were before the path changes too). Will discuss this in a separate ticket: #1873

[strk]

This is done for now