The files in this directory test various aspects of reactions.  These are
derived from the tests I used for validation against old mcell behavior, as
well as against Boris' trimolecular code when I merged with macromolecules.
I'll give a summary below of what each file is, with more detailed information
in the header of each MDL file.

Note that most files which use the trimolecular pathway have TIME_STEP_MAX set
to 1.0.  They all should, I think.  The trimolecular code doesn't seem to
safely use safe_diffusion_step, so in order to make fair comparisons for
correctness, I turned off adaptive timesteps.

 * Test 01: All volume rxn types, traditional + trimol. code paths
 * Test 02: Same as test 1, but without ACCURATE_3D_REACTIONS
 * Test 06: All surface rxn types (vol surf, surf surf, vol vol surf, etc.)