Regression test for the simulation models.
Use
	./run_spice_tests.py essential.txt

The "essential.txt" is a list of devices that simulate after manually
removing a number of different devices which are lacking layouts,
models, paramters, or which are not well understood.

The script runs ngspice on each of the devices in "essential.txt" and
produces a single value, which is:

	beta for bipolars
	Vth  for FETs and diodes
	R    for resistors
	C    for capacitors

The value measured is placed in "baseline_results.txt" in this directory.
Output from ngspice is accumulated in "output.log".  The generated
netlists, results, and graphs in SVG format can be found in the
results/ directory.

The terminal output of the command is the output from ngspice, followed
by a summary of which devices failed or passed simulation, followed by
a total count of failing and passing devices.
