sdvplotR keeps the team index, the logo manifest and the NFL
headshot map in memory for the session, keeps the index and manifest on
disk (in tools::R_user_dir("sdvplotR", "cache")) for a day. This clears
them, the images it could not read this session, and the image cache of
'ggpath' when 'ggpath' provides a way to, so the next call reads the CDN
again.
See also
sdv_versions() for what is loaded now.
