Added variable number pred-pars files entries for Will.  New option is
called --post-pred-ran-ns.
Include --multi-fix-mix to allow multiple mixed fishery simulations

This new option allows the simulation of multiple mixed fisheries of
sizes and composition as specified on the command line.  Did this to
allow more efficient simulation for the lower granite dam project
with the idaho guys.
added xcode files to the repository

only added the xcode and my user files, not all the build products
and debugging stuff.
added a .gitignore file
added TERMS.md and made README a markdown file
updated .gitignore