Removed connected tracks variable.

This contained redundant information, as all connected tracks
would be stored in an intersection
Fixed a bug where a moved track was incorrectly marked valid
Changed for type loop to prevent concurrent exception

Also added new test to ensure that a new intersection isn't
created when moving an intersection
Changed criteria of remove intersection test
Tracks are disconnected after intersection dissolves

If a track was an active next track to another, they would
still appear to be connected after the intersection
was deleted