Handle stochastic test suite OMEX files

[luciansmith]

The SBML Stochastic Test Suite has models that should be simulated stochastically many times, then the averages and standard deviations are collected. I've created an OMEX file that should handle this, but unsurprisingly, it uses SED-ML features that nobody has ever implemented support for before. Let's implement support for them!

00001.omex.zip