customize font, display date, clean requeries, license change, &c.

- changed license to GPLv3
- allow user to specify font name and height for display
- place date/time stamp above location name at top of buffer
- re-query with new location deletes to reduce buffer clutter
- updated screenshot to show current updates
- changed references from "city" to "location" in wttrin.el
- removed old CI config files
- removed old badges from readme file