Probabilistic FIM Prototype

[TylerSchrag-NOAA]

This PR contains my work-in-progress efforts on Probabilistic FIM (really more like Ensemble FIM, as this is only the simple implementation we discussed of overlaying ensemble inundation extent polygons to simply visualize probability without precise quantification).

This PR is incomplete, and should be further developed before merging.

Here are the general steps that were discussed for developing an initial version of Probabilistic FIM:

• Implement FIM Caching Enhancement so that more FIM can be processed without as much compute/cost
• Draft map of ensemble members overlaid with transparency, to show simple probability - I'll paste the latest draft in a comment below, which I didn't hear back on. I've included the mapx of this visualization in this PR for further tweaking.
• Develop MRF 5-Day ensemble FIM (this is essentially done, per the files in this commit, but may need some tweaking based on actual testing).
• Develop SRF 12-Hour ensemble FIM (I was thinking that I had started this, but can't find my files, sorry Shawn).

[TylerSchrag-NOAA]

Most recent rough draft visualization: