Document netcdf outpuf format

[pmav99]

I think it would be really useful if the netcdf output file was documented (variables, dimensions etc). If the solvers produce output files with different formats then we should document what each solver produces separately. As soon as things are relatively stable, changes in the output format should require a version bump.

The documentation can be either an ipython notebook or a wiki page (or both! :P).

[pmav99]

The current netcdf file has the following variables:

['Cs',
 'SCHISM_hgrid',
 'SCHISM_hgrid_edge_nodes',
 'SCHISM_hgrid_edge_x',
 'SCHISM_hgrid_edge_y',
 'SCHISM_hgrid_face_nodes',
 'SCHISM_hgrid_face_x',
 'SCHISM_hgrid_face_y',
 'SCHISM_hgrid_node_x',
 'SCHISM_hgrid_node_y',
 'coordinate_system_flag',
 'depth',
 'dry_value_flag',
 'edge_bottom_index',
 'ele_bottom_index',
 'elev',
 'hvel',
 'minimum_depth',
 'node_bottom_index',
 'sigma',
 'sigma_h_c',
 'sigma_maxdepth',
 'sigma_theta_b',
 'sigma_theta_f',
 'time',
 'wetdry_elem',
 'zcor']

which of those are necessary for visualization?

[brey]

For our purposes now it is only 'depth' and 'elev'. However if the API includes additional functionality of the SCHISM ecosystem there could be more. Since this is defined by the user, we should have the complete NETCDF available for visualization.