Fixed explore_counties() man pages.
In shiny_choro, no need to check args lengths before match.arg().
Simplified imports in shiny_choro. Also, fixed file.copy error.
Cleaned up some docs in shiny_choro.
Some cleanup in the Shiny app.
Improved shiny_choro's initial loading speed. #26
Slight speedup/cleanup in Shiny server.r
Shiny app is slightly faster when filtering. #27