Update 1.5 (13.10.2018):
- symmetrize - merged into Mirror tool.
- Mirror Tool - added ‘All groups’ option, to mirror all groups in selection (not just active group).
- Mirror - Project - New tool same as above, but work with meshes that have non symmetrical topology.
- ‘Draw Weights’ addon - added ‘Merge colors’ option. With it left and right bones will have same color.