Use local timestamps for day summaries

[Nate-Wessel]

This will require a spatial timezone lookup when points are created. Several libraries are available. Current timezone is UTC across the board.

[Nate-Wessel]

A spatial lookup was extremely slow with the timezonefinder package. Implemented a config parameter for local time for the moment.

[Nate-Wessel]

It might be sufficiently efficient to look up one arbitrary point in each episode and use that timezone in all points in that episode.

It would be good to time the timezone lookup function to see if the benefit is worth the likely delay.

[Nate-Wessel]

If we just insist that all coordinates provide a local timezone name/offset then we can just use that in the output. There are lots of timezone boundary files that should make this pretty easy to do before hand for data that doesn't already have that set.

[Nate-Wessel]

https://github.com/evansiroky/timezone-boundary-builder