Add a regression test to show that the proper dumpfile is selected, by
noting in the output from the vvp command what file name it is creating.
To make this work, I also needed to add some capabilities to the vvp_reg.py
regression test rig.
This creates a new test suite driver and infrastructure for going
forward. This cleans up the descriptions for tests, and is more
extensible.
Include documentation for the new engine, so that new tests can go
here instead of the old test suite.
Stephen Williams