usmap 0.5.0

Ability to include county name labels on county maps, see Issue #14.
- They currently work the same as state labels except they include the full county name (excluding the word “County”).
Ability to pass ggplot2::geom_polygon() parameters to plot_usmap(), see Issue #15.
- This is a breaking change and removes the lines parameter. The previous defaults of color="black", fill="white", and size=0.4 are maintained and will be used for any of those parameters that are omitted.
- Refer to the ggplot2::geom_polygon() documentation for more information.
- The following aesthetics are supported: alpha, colour/color, fill, linetype, size
- This feature provides more direct control over the appearance of plots.
Ability to exclude counties and states with new exclude parameter in us_map, map_with_data, and plot_usmap, see Issue #19.
New function (usmap_transform) to transform longitude/latitude point data frames into coordinate reference system that matches the plotted map, see Issue #21.
- Also includes usmap_crs() to easily access the coordinate reference system used by the package.

In the data frames provided by us_map(), long and lat have been renamed to x and y, respectively, see Issue #16.
- This should not affect the behavior of plot_usmap() but will be a breaking change for any code that relies on us_map().
Added contributing guidelines and templates, see Issue #24.
- These can be see in the .github folder.

usmap 0.4.0

Ability to include state abbreviation labels in state maps, see Issue #9.
- e.g. plot_usmap(labels = TRUE)
Add US Census Bureau regional divisions as constants for quick plotting of certain regions.
- e.g. plot_usmap(include = .northeast_region)
- The provided regions and divisions can be seen on this map by the US Census Bureau.
Allow ability to include only certain states while viewing county map, see Issue #11.
- e.g. us_map("counties", include = "TX") or plot_usmap("counties", include = c("AZ", "NM"))

Vectorize counties in fips, see Issue #10.
- e.g. fips("NJ", c("Bergen", "Hudson"))
Allow all columns in the data frame that’s passed to map_with_data() or plot_usmap() to be preserved.

Add Kusilvak Census Area (FIPS code 02158), replaces Wade Hampton Census Area (FIPS code 02270).

Update shape files to 2017 versions.
Improvements to fips and fips_info:
- Vectorization support (e.g. enter multiple states in fips to receive a vector of corresponding FIPS codes)
- e.g. fips(c("AK", "AL")) or fips(c("Alaska", "Alabama"))
- Mixed abbreviations and full names are also supported: fips(c("AK", "Alabama"))
- Improved warning and error messages.
Allow data to be specified by state abbreviation or full name in plot_usmap and map_with_data (instead of just by FIPS code).
- The data frame passed to plot_usmap or map_with_data (via the data = parameter), can now be a two column data frame with columns “fips” and “values” or “state” and “values”.

Standardize documentation language.
Improve descriptiveness of error messages and warnings. ### Bug Fixes
Allow data passed to map_with_data and plot_usmap to contain FIPS codes with missing leading zeros.
- This usually occurs when the codes are read as numeric from a .csv file.

Add map_with_data function for adding user-defined data to map data.
Add ability to plot map with data automatically (utilizes new map_with_data function).