investigate adding functionality from gridMap_correlation.R

[jonathancallahan]

All of the code in local_R/ is code left over from the previous version of the package. Each of these functions needs to be evaluated as to whether it is useful and still needed in the AirFireModeling version of the package.

This task is to investigate creating an updated grid_correlationMap() function, using the old gridMap_correlation() as a starting point.

The original code use base R functionality and this is a chance to evaluate options for improvement including:

• Should we use ggplot for mapping?
• Should we harness capabilities available in RasterVis or some other package? What would be involved in that?

The end result of this issue will be the creation of more specific tasks.

[hmrtn]

Yes, this looks like it can be added. As for its purpose - I see it as important, too. We need to review the use of our correlation algorithms.

[hmrtn]

Added