separate undo history for sculpt mode, same as edit mode

sometimes you're not happy with your sculpt changes, only to find that they've overwritten the full undo history, so there's no way back (unless you save before entering sculpt mode each time).

Would be cool to have the undo's stored seperately the same as edit mode, so you can undo all the changes in one go.

Or perhaps better still have multiple undo tree's so you can undo individual changes from the different modes.