refactoring river-routing

[weiyuan-jiang]

@YujiN, I am trying to bring back some codes in develop branch. The develop branch is not working as it is but I believe it would be more efficient. The runoff and the other variables are distributed as needed, which is way more efficient than allgatherV.

[weiyuan-jiang]

@zyj8881357 and @gmao-rreichle , I have made some changes:

1. Added a new catchment space which can be used in Internal ( restart) and History output. https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/3bf435f7614657329592c60f8b75509656e353a1/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSsurface_GridComp/GEOSland_GridComp/GEOSroute_GridComp/GEOS_RouteGridComp.F90#L722C5-L722C65

2. Added mapping from tile space to catchment space . https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/3bf435f7614657329592c60f8b75509656e353a1/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSsurface_GridComp/GEOSland_GridComp/GEOSroute_GridComp/GEOS_RouteGridComp.F90#L724C5-L724C67. It can be used here
   , which would replace the codes
   

3. Added subroutine to exchange downstream.

   GEOSgcm_GridComp/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSsurface_GridComp/GEOSland_GridComp/GEOSroute_GridComp/GEOS_RouteGridComp.F90

   Line 734 in 3bf435f

   call setup_exchange_cat(_RC)

   . It is zero-diff and quite efficient. It exchanges about 4 or 5 values each processor instead of 300K. It would be used
   here and replace the codes
   

4)Also all the outputs ( including check balance) and restarts will be replaced by the simple codes like this

[weiyuan-jiang]

To make further changes, we should start with make_bcs to produce necessary files

[weiyuan-jiang]

@zyj8881357 , I think this PR is ready for the test and comparison. To run this branch, you will need the develop branch of GEOSldas and feature/wjiang/pfaf_index of MAPL. Also please take a look at my run example in /discover/nobackup/wjiang/LDAS_exp/model/Routing
You will need three files : route_internal_rst, tile_pfaf.nc4 and river_input.nc
Please diff my LDAS.rc with yours and change yours accordingly to run the program. The route_internal_rst is not the same as yours. I am using the second day's restart (20140102 000000). You can create your own restart.

[gmao-rreichle]

cc @gmao-rreichle