3D viewer: fix wrong index for compact-json access
3D viewer: fix wrong index for compact-json access

In commit ade90b8 I removed the reviewer field from the treenode representation
in the compact-json API. Therefore many indices had to change that are used to
access the response object. One index was forgotten, which is fixed by this
commit.

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