Working implementation of _MappedFlatField
Figured out how to instantiate without making a copy of the range
values!
[1594]
First stab at getVIIRSImage.

- depends on IDV pull request 84
- only been testing on single-banded files from PEATE.

[1594]
Merge pull request #96 from mhiley/viirs-scripting

First stab at scripting function for VIIRS imagery [1594]