Add scrape of outer edge of domain so water doesn't pile up.

[aubreyd]

TYPE: bug fix

KEYWORDS: overland flow

SOURCE: Aubrey D., NCAR

DESCRIPTION OF CHANGES: In the 1D overland flow scheme, the outer edge cells are not properly treated (they are in 2D scheme). This can cause water to pile up on the edges, particularly with limited infiltration (e.g., glacier cells). We do a brute force method here to scrape water above maximum retention depth from these outer cells and capture it in QBDRY. This should someday be updated to match the 2D approach.

ISSUE: The GitHub Issue that this PR addresses. For issue number 123, it would be:

Partially fixes #657

TESTS CONDUCTED: Tested fix over NWM-Alaska cutout domain and water no longer piles up on edge. Tested NWM-CONUS and confirmed minimal impacts (only along edges), passes ncores, passes perfect restart.

Checklist

Merging the PR depends on following checklist being completed. Add X between each of the square brackets if they are completed in the PR itself. If a bullet is not relevant to you, please comment on why below the bullet.

• [x] Closes issue #657 (An issue must exist or be created to be closed. The issue describes and documents the problem and general solution, the PR describes the technical details of the solution.)
• [na] Tests added (unit tests and/or regression/integration tests)
• [x] Backwards compatible
• [na] Requires new files? If so, how to generate them.
• [na] Documentation included
• [na] Short description in the Development section of NEWS.md

[rcabell]

Should edge_adjust be REAL*8, since it's adjusting variables of the same type?

[aubreyd]

We are keeping real*4 since these are not incremental additions, just batch at end. Removed confusing comment.