Remove dead code from odesys.c
Add some comments to odesys.c
Add some TODO items
Add AUTHORS file
Write time of each step to output file as an hdf5 attribute.
Fix checking of the number of supplied cli arguments.
Fix handling of terminal null when slurping file to buffer.
Remove linear_molecule_dispatched_dtor and consolidate
Initial pthread support. Working, but needs cleanup.
Move GSL related structures out of odesys_t and into a new structure
odegsl_t.

This greatly simplifies the code using pthreads, since each thread
cancreate its own odegsl_t structure, and we don't have to copythese GSL
structures during the shallow copy of odesys_t before passign to each
thread.