MARBL code guidelines

Code modifications

1. Fork the NCAR/MARBL repository (github will keep it private)
2. Do all of your work on a branch in your own repository
3. Submit a pull request back to master on NCAR/MARBL

FIXME comments in the code

1. Before making a new FIXME comment, make sure an issue ticket for the problem you want to address exists (or create a new ticket)

2. Include this ticket number in the FIXME comment

   ! FIXME #00: Make sure it is easy to figure out what issue ticket
   !            a FIXME in the code refers to
   

3. Before closing an issue, grep for the issue number to make sure you cleaned up all instances of the problem.