This greatly improves the mesh edit tabs after a few weeks of feedback, making the tabs more practical with less need to switch tabs often. Based on discussion on IRC and T37568. Reviewers: campbellbarton CC: campbellbarton, brecht Reviewers: campbellbarton Reviewed By: campbellbarton CC: campbellbarton, brecht Differential Revision: https://developer.blender.org/D269