Change contour example to use lowercase columns
Change contour example to use lowercase columns

The weather data from water.weather.gov changed casing on some
attribute names to be all caps, from just capitalized (or geopandas
reads them in differently). To be slightly more robust, change
all the columns to be lowercase and use the new names instead.

ocefpaf/mplleaflet,jwass/mplleaflet,BibMartin/mplleaflet,zeapo/mplleaflet,BibMartin/mplleaflet,jwass/mplleaflet,zeapo/mplleaflet,ocefpaf/mplleaflet