Devel/netcdf

This closes #16 (closed), providing an updated netcdf output format to be used in further development. Includes a single boundary condition file written at the first time step and a refactoring of the netcdf_writer module. Most importantly, move the mod_model out from the bolam.f90 allowing for the unpacking of the code in a more rational method. Everything is now under the netcdf_writer module.