When was set use_external_mp_once to true then after first calling the avoid crossing perimeters this flag was reset which cases that on the second call of the avoid crossing perimeters the travel move didn't process as external.
The strategy for the avoid crossing perimeters algorithm has been redesigned. But external travels (travel between objects or supports) have not been solved yet. For these travels is used a direct path between two points.
Much of the code has been reworked, which leads to significant speedup compared to the previous implementation.
Also, several potential bugs have been fixed.
