MITgcm driver using f90nml
Environment variables are now always converted to strings
Merge branch 'master' of https://github.com/marshallward/payu
Fixed some mitgcm nml parsing typos; removed commented code
13: payu build command builds all models. Still relies on Experiment.
13: fix bin_path which is now in lab not expt.
13: make --laboratory argument carry across resubmits.
13: missing update from GET_env_vars to SET_env_vars.