Create function to export data for GeoCLIM

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Export data in format for GeoCLIM https://earlywarning.usgs.gov/fews/software-tools/20

Daily, dakadal and monthly output should be possible.

Example format for monthly output attached.

GEOCLM-PRECIP.csv
GEOCLM-TMPMIN.csv

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Format specified in Section 3.3 of https://edcintl.cr.usgs.gov/downloads/sciweb1/shared/fews/geoclim/GeoCLIM1.2.1_Manual.pdf

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3.3. Tables
The GeoCLIM program uses tables in comma-delimited format (*.csv) as input and output
data. For example, tables are inputs in the process of blending raster data with station values
(BASIICS) or validating raster data. For the blending process, the CSV table must have columns
for ID S, latitude (lat), longitude (long), year, and time period (pentads, dekads, or months), such
as the months of January-December in Figure 3.4. The ID, lat, lon, and year columns do not have
to be in any particular order, and additional columns are permitted. However, the time-period
columns need to be consecutive (Figure 3.4).

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GeoCLIM monthly export now done.

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GeoCLIM documentation only mentions monthly, dekad and pentad output formats. Daily is not implemented in Climsoft either.
If daily is needed it can be added.