We are running out of letters for the command line options, which are becoming increasingly
less memorable, so this is an attempt to introduce GNU style long arguments like --self-gravity
to extend the range of possible options and make them more self describing.
I've added a small amount of code from another project, rather than using getopt_long,
as the latter is not POSIX, and the code I found is well written and provides a good
basis for what we need. The licensing is compatible with the GPL, although not the same (MIT/X11).
This also brings the documentation of the option to the same place as the definition and
allows grouping, so we have simulation and basic control options separated.
@nnrw56, @matthieu, @jborrow, @lhausammann how does this look to you?
The next stage would seem to be to release some of the single character options from the less used options...