macro args now correctly preserve range positions

Somewhen in the 2.11.0 development cycle we started duplicating macro arguments
for increased robustness. What wasn't taken into account though is that
Tree.duplicate destroys range positions. This commit fixes the problem.

2.10.x is unaffected by this bug, because it doesn't duplicate the args yet.
Merge pull request #3780 from xeno-by/topic/rangepos-macro-args

macro args now correctly preserve range positions