[arrowDoubleInverted] Bugs

[DarianFlorianVoda]

• [ ] Scale correctly on test 3
• [ ] d.head = -1.5 should duplicate the right/left part
• [ ] On test 2 for "join innermost ">" the testArrow fails

[discoleo]

[FIX] arrowHeadDoubleInverted

• error in this function: missing scale = scale in one of the shiftPoint();

  pV = shiftPoint(c(x, y), slope=slope, d = d2, scale=scale);

[DarianFlorianVoda]

Added