Adding ONE_TRACER_SOURCE option, first stab.
Dry mask on srflx, rmask_wet in stations, etc.
Added masks for WET_DRY tracer control. Other small changes.
Formalize NO_DRY_TRACER_CHANGE even though I'm not using it now.
Added u/vmask_diff for WET_DRY. Added wdiv for ice divergence output.
Multifile patch for CLM.
Fixes from John Warner.
src:ticket:637

git-svn-id: https://www.myroms.org/svn/omlab/branches/arango@1578 f091316a-d328-0410-a40a-876eff57d070

Conflicts:

	ROMS/Nonlinear/step3d_uv.F
src:ticket:640

git-svn-id: https://www.myroms.org/svn/omlab/branches/arango@1579 f091316a-d328-0410-a40a-876eff57d070
src:ticket:642

git-svn-id: https://www.myroms.org/svn/omlab/branches/arango@1580 f091316a-d328-0410-a40a-876eff57d070