obisindicators 0.0.2

Renamed functions for consistency:
- calc_es50() -> calc_indicators()
- gmap_metric() -> gmap_indicator()
Fixed gmap_indicator() to use default Robinson projection.
Updated vignettes with name changes and use of "indicators" over "metrics".
Supplemented documentation for calc_indicators() with expected input and output columns to data frame.
Added documentation for occ_fk and occ_1960s to occ_2010s
Made generation of occ_* datasets more reproducible with set.seed() and sampled versions of dataset to minimize file size on Github in data-raw/occ.R.

obisindicators 0.0.1