changes to reference docs.  before rebuilt package.
improve cache load data function for reading tables. add multiplot
add back in counts of annual, monthly, and seasonal records per gages. allow customization of gage id column. allow overwrite of gage shapefile.
replace code with cache load data function.  clean out unused code.
update data merge to allow customized id col names
rebuild package
vignette for data prep.  includes comments, but need to add full descriptions