Topotools branch updated to 5.1.0

I merged master (v5.1.0) into topotools and also added a few new commits, including some improvements to fgmax support.

I added topo1writer, topo2writer, get_topo from the old topotools.py so that the nosetests would run.

The chile2010 example needs updating for the new Okada routines, doesn't run at the moment.