nflplotR 1.1.0

• nflplotR will internally cache images used in all geoms and elements. The cache behavior can be controlled by setting options("nflplotR.cache") to one of "memory", "filesystem", or "off". It is possible to clear the cache with the new function .nflplotR_clear_cache(). This functionality added the dependencies cachem, memoise and rappdirs.
• Resolved an issue where geom_mean_lines() and geom_median_lines() didn't draw lines when a scale transformation, e.g. scale_*_reverse(), was applied.
• Added new function nfl_team_factor() which creates ordered factors of NFL team names for facetted plots.