Selected node(s) can now be moved up and down in scene tree dock.
Restricted to same parent, seem to work better now.
Fix crash when gd-script _init fail
Small clean-up..
Merge pull request #987 from sanikoyes/Pr-crash-in-scrip-init

Fix crash when gd-script _init fail
Merge pull request #986 from TheoXD/_tree_multiselect_move

Selected node(s) can now be moved up and down in scene tree dock.