Implement a robust solution for problematic boundary condition lines to external face mapping in HEC-RAS hdf5 results file

[jrutyna]

Issue #6 identified an issue with the way HEC-RAS mapped boundary condition lines to external faces in its hdf5 results file; a bug report has been sent to the HEC-RAS development team regarding this issue. A work around solution was implemented for issue #6 for the example simulation comparison between an EFDC model of the Ohio River and the same system in HEC-RAS/Clear Water.

A more robust solution will be needed to handle these problematic boundary condition lines if the HEC-RAS development team does not resolve the issue or before they release the update. The two proposed solutions that @jrutyna identified in issue #6 that could be implemented within the Clear Water framework are:

1. Develop a similar geo-processing tool that HEC-RAS performs to identify external faces from the boundary condition line, or
2. Develop a method from the face flow results to identify which external faces have flows coming in/out of the model domain and use these faces as a lookup in the Geometry/Boundary Condition Lines/External Faces table