Fix infinite loop bug in error module. Closes #150.
Update instructions for MPICH2/OpenMPI.
Change abundances.txt so each element sums to 1.
Update isotopic abundances to IUPAC 2009.
Rewrote readme.rst.
Fixed license section in readme.rst.
Updated mailing list link in readme.rst.
Updated a few things in documentation.
Change statepoint_batch to type(SetInt).
Added source_write option to inhibit writing source sites in state points. Closes #153.