Improve work with the track laps

There are multiple requests to add lap functionality.

For instance:

https://help.locusmap.eu/topic/include-laps-in-tcx

https://help.locusmap.eu/topic/laps-tab-on-the-track-details-screen-%E2%80%93-possibility-of-displaying-data-between-waypoints

https://help.locusmap.eu/topic/kfiph8nrhsk2j

I'd like to propose to add laps in 2 ways: manual & auto

Adding a lap button to recording panel (and/or widget) would allow for manually adding laps (for interval training for instance) while recording a track.

In combination with maybe audio trainer there could also be the option to record laps automatically, every 400m or every 3 minutes.

Exported files (tcx) could contain those lap information for to use in analytics tools (runalyze, etc).