(1) A lake_depth_flag is added in REAL and WRF to make it clear whether the lake_dept...

(1) A lake_depth_flag is added in REAL and WRF to make it clear whether the lake_depth information is included in input data (thanks to Dave for helping with the FLAG).  REAl will not stop if this information is missing while Lake model is turned on. A warning message will be issued to remind the  users to include the lake_depth data in WPS.  Codes related to lake model initialization is revised.

(2) The namelist option "LakeModel" is replaced by "sf_lake_physics" in Registry. Related codes are changed.

(3) A new namelist option ( i.e., use_lakedepth in &physics)  is added  to give the users clear idea whether and how they should use the lake-depth information.

M    phys/module_sf_lake.F
M    phys/module_physics_init.F
M    dyn_nmm/module_PHYSICS_CALLS.F
M    dyn_nmm/start_domain_nmm.F
M    share/module_optional_input.F
M    share/output_wrf.F
M    run/README.namelist
M    Registry/registry.lake
M    dyn_em/module_initialize_real.F
M    dyn_em/module_first_rk_step_part1.F
M    dyn_em/start_em.F

git-svn-id: https://svn-wrf-model.cgd.ucar.edu/trunk@7290 b0b5d27b-6f0f-0410-a2a3-cb1e977edc3d