(*)Oil_tracer_column_physics unit conversion fix

  Added a missing unit conversion factor to a hard-coded 10 m distance in
oil_tracer_column_physics.  This will not change answers in Boussinesq cases
without any dimensional rescaling, but it will correct answers in a hypothetical
non-Boussinesq case.  Also made some white space in expressions near this fix
more closely match the MOM6 style guide. No answers are affected in any known
existing regression test cases or other runs.

src/tracer/oil_tracer.F90

@@ -373,21 +373,21 @@ subroutine oil_tracer_column_physics(h_old, h_new, ea, eb, fluxes, dt, G, GV, US
   ! Add oil at the source location
   if (year>=CS%oil_start_year .and. year<=CS%oil_end_year .and. &
       CS%oil_source_i>-999 .and. CS%oil_source_j>-999) then
-    i=CS%oil_source_i ; j=CS%oil_source_j
-    k_max=nz ; h_total=0.
+    i = CS%oil_source_i ; j = CS%oil_source_j
+    k_max = nz ; h_total = 0.
     vol_scale = GV%H_to_m * US%L_to_m**2
     do k=nz, 2, -1
       h_total = h_total + h_new(i,j,k)
-      if (h_total<10.) k_max=k-1 ! Find bottom most interface that is 10 m above bottom
+      if (h_total < 10.*GV%m_to_H) k_max=k-1 ! Find bottom most interface that is 10 m above bottom
     enddo
     do m=1,CS%ntr
-      k=CS%oil_source_k(m)
+      k = CS%oil_source_k(m)
       if (k>0) then
-        k=min(k,k_max) ! Only insert k or first layer with interface 10 m above bottom
+        k = min(k,k_max) ! Only insert k or first layer with interface 10 m above bottom
         CS%tr(i,j,k,m) = CS%tr(i,j,k,m) + CS%oil_source_rate*dt / &
                 (vol_scale * (h_new(i,j,k)+GV%H_subroundoff) * G%areaT(i,j) )
       elseif (k<0) then
-        h_total=GV%H_subroundoff
+        h_total = GV%H_subroundoff
         do k=1, nz
           h_total = h_total + h_new(i,j,k)
         enddo