Demo mode

In this release I added support for Demo mode - basically read only mode where all write capabilities are disabled and admin UI is also read only. I'm planning to create a public demo instance - final preparations are in progress. For regular users it doesn't change anything, it should not impact existing functionality.

Encryption secret for OwnTracks

GeoPulse now supports encryption secret for OwnTracks (both HTTP and MQTT modes). See details - https://owntracks.org/booklet/features/encrypt/
It is optional only for those who want to encrypt messages on OwnTracks side.

Max speed for bicycle - 80km/h

Changed max allowed speed for bicycles from 50 to 80 km/h

UI improvements on mobile

Implemented some UI (mainly timeline-related) improvements on mobile devices.