Add null checks to the Motion methods.
Add moving to the path start point, fix linear segment movement

The hotkey for this action is CTRL + Recording key (default: M)

NOTE: Currently it moves the player to the linear path's target point
and not the first path point, because we need to rework the path stuff
a bit, both for this and also for saving the points to file, and
supporting multiple paths.
Add null checks to the move to start point functionality
Refactored the path stuff. It now supports multiple paths.

Note: The "linear" and "smooth" modes now use the same set of points.