Assumes the IFOModel is given as function in .m script, and use Matlab
engine interface to execute and load.

Add wrapper Matlab class that provides cleaner more useful interface to the
matlab.engine.  The engine itself is held as a global variable, so that it
doesn't need to be passed around for multiple invocations.

clarify PRFixed to be bool and True by default

Error is:

  jobs:test:cache:key config cannot contain the "/" character

Updates to materials parameters for new thermal noise estimate, and SRM and
PD params.

 https://dcc.ligo.org/LIGO-T1800044

no functional change

Functions now expect separate (freq, psd) numpy array args

Use IFO name

closes #6

This directly compares the output of gwinc() and gwinc_matlab().  Any
noises that differ by more than 1% are noted and the return value of the
test is non-zero.  Differences can be plotted with the -p option.

This makes output directly comparable with pygwinc output

with --fom option

The return values are now commensurate with gwinc_matlab, making them
essentially interoperable.

addresses #2