This diff adds a new loader class SWHSvnLoaderFromRemoteDump enabling
to load svn repositories in an incremental and efficient way.
This is a first draft in order to share the idea and the results.
The loader is based on the creation of dump files generated with the
rsvndump tool. It is not packaged in Debian so you must get it from
http://rsvndump.sourceforge.net/ first, then compile and install it.