Add support for tcsh

In addition to adding support for tcsh, this adds testing for bash and tcsh that was previously non-existent. 

This also moves the documentation into the project (and out of pydocs).

In addition to self tests, I ran a regression test on acisfp_check.  This uses Spawn (which was unchanged), but I thought it a good anyway.

The new bash unit tests also pass on the flight version, so there should not be any regressions introduced by the refactoring.