Terrain-following vertical coordinate overhaul

[arango]

This is a major redo of ROMS vertical coordinates. It was expanded to support and additional transformation and numerous vertical stretching functions. The original transformation and vertical stretching function is still available.

All the input scripts were modified to include two new standard parameters:

! Set vertical, terrain-following coordinates transformation equation and
! stretching function (see below for details), [1:Ngrids].

  Vtransform == 1                          ! transformation equation
 Vstretching == 1                          ! stretching function

There is extensive documentation about this in standard input script and ​WikiROMS. Also check the following message in the ​forum.

Many thanks to Sasha Shchepetkin for providing us his tranformation and vertical stretching function (available in UCLA-ROMS as default), Rocky Geyer for providing us a new vertical stretching function for sediment applications in shallow grids, Andy Moore for his help checking these transformations in the adjoint codes, and Rich Signell for his help with CF conventions Committe and the NetCDF-Java Group.