Custom local mirror plane/normal for sculpting

Why:
Allow symmetrical sculpting in specific spots on the model. This allows for cleaner and controlled creation of surface details. Especially for organic objects that are not naturally symmetrical.

Enabling radial symmetry would also make it very easy to create equally spaced details.

How:

• Accessible in the same panel where the brushes reside ( makes sense to put it next to the transform tools )
• Once activated, a widget that looks like a plane with a normal axis ( local z )widget appears that you can freely move around in 3D space. This widget can be translated and rotated. With face snapping it would be easy to accurately place the widget. Snapping to 3D cursor should also be possible.
• Should work together with the global mirror settings.
• Modes
  • Plane symmetry allows you to sculpt in the plane's local x/y axis.
  • Normal symmetry allows you to sculpt around the plane's normal. The mirrored point is always on the opposite side. With radial options more points can be added.
  • Active Mode is indicated by whether the plane or normal is highlighted.