Track recording

[cdauth]

Add an option to record a line.

It could be an item in the tools menu that opens a dialog where the recording can be configured. Starting the recording will open a search box tab where the recording can be paused/finished.

In the recording dialog, the user can select any line type. Maybe the recording intensity (time/distance interval per trackpoint) can be specified.

An indicator could show the current length of the recording.

A line that is being recorded should appear live for other users, but it is read-only for them until the recording is finished. The recording user should be able to change the line data already while recording (through the recording tab).

A new Socket API endpoint needs to be added to record a line and add track points to it. When the socket loses connection, the recording is finished.