web interface

- more configurable parameters
	- plane ttls
	- OSM tiles source URL
	- AJAX data source URL
- remember more ui settings in local storage
	- which map type was viewed
	- plane table sorting direction, field
- ui changes
	- indicates when plane on ground
	- shows empty box in table when not receiving value (like CLI interactive UI)
- fixing etc.
	- plane was selected, ttl'ed, then came back, had selected marker color
	- memory leaking (orphan dom nodes, seemingly), so remove old elements on refresh
	- more robust handling for server disconnects, restarts
- code refactoring
	- refactor dynamically generated HTML elements and create DOM elements instead
	- added functions for new code used multiple times