- If the mirrored group doesn't exist yet, it creates that group now. - Painting on any non-mirror group (not a name complying mirror rules), it will now paint mirrored on the group itself. - The Mesh octree for mirror painting was not created on loading a file in WeightPaint mode, or on exiting Editmode for Mesh. This caused mirror painting to not work always. - Tweaked the threshold calculation for vertices, so it gives fewer misses.