naijR 0.6.0

New Features:

Added a new dataset states_nigeria for the States of Nigeria.
Migrated from RGDAL-based spatial data; the {sf} package is now the main dependency.
map_ng gained a newly documented argument plot, which hitherto was passed internally to maps::map() via ....
Added a new function disambiguate_lga, which takes a single-element lgas object for handling the names of Local Government Areas that are shared between separate States. This function enables the (re)setting of the State attribute of such objects; this can be done interactively, where the replicated States' names are presented for selection by users.

Improved on the accuracy of LGA naming in the light of spelling mistakes discovered in the earlier reference document.
Unwanted display of dialogs when fixing LGA names on Windows OS was reversed (suggested by Laura DeCicco).