Uses the National Map Aerial Image REST API to return an aerial image to be
used as a basemap. May add functionality for 1m or 1ft images. May also add
topo-map.
# NOT RUN {#Can be run alone to get jpg, but best if run through qmap()data(lake)
x<-qmap(lake,buffer)
x_base<-get_basemap(x,'1m_aerial',width=1000)
x<-qmap(x_base)
# }# NOT RUN {# }