#2373 Improve connectors heads when lines are hidden to reflect correct/actual directions

[Cadux]

Hi.
Recently Freeplane's connectors were improved, allowing to hide/show connectors lines. The new functionality brings much power to connectors be used more often, since now it is possible to use plenty of connectors without messing up the visual of the map.
However, when lines are hidden, the arrow heads don't reflect the correct/actual direction of connectors.
I suggest to improve the visualization of arrows when lines are hidden in order to reflect correct/actual direction.
I've attached a suggestion, in which I tried to position the arrow heads to reflect direction of connectors.
Thanks for considering it!
Carlos_Cadu