Removed unused function reroot_treenode from treenode.py
Removed unused function reroot_treenode from treenode.py

fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,htem/CATMAID