Timesteps per vis

This works as intended and it's the minimal changeset, so it should be ready for merge as-is, but the current output indexing is a bit weird.  The initial conditions are unnumbered, then the end of the first timestep gets a number 0, etc.  Could we make the ICs output number 0, the end of the first timestep number 1, etc, instead?  That way asking for every timestep would give us "0", "10", "20", etc. rather than "", "9", "19", etc.