We hadn't actually updated version info since 0.7.1. This will be the only
change before cutting a new release tag. There will be no need to re-deploy
to the Dev edge, which received v0.8.0 already.

Update version to 0.7.1 in setup.py

Added the prefix 'imf' to denote intermagnet format.

These files add modules to write timeseries out in json format.

to geomag.py