Tidy up
Made datapoint and freegeoip interfaces datatype agnostic.
Created retry function in utilities to be used
when a url might fail or when the url might return
partial data.
Dewpoint calculated from temp and humidity
Added option to autolocate.
Removed option for multiple locations.

Future work on this plugin will make multiple
locations unworkable, since a location can be
set for different weather aspects, eg, region,
mountain, observation, forecast. In these cases
"Location1" would have no meaning.
Added default API Key

Also moved WEATHER_WINDOW assignments so they always get made.