Fills in the mesh's merge information so it can become a solid again: vertices on open edges within the tolerance are merged, keeping existing entries.
A mesh that is already closed is left alone and false comes back. Meant for a mesh whose merge data was lost in a file; the rebuilt solid reports a status if still open.
The mesh to repair
True when the mesh was changed, false when it was already closed
Repairs on Manifold mesh data before it is turned back into a solid; today that is
merge, which restores the merge information a file round trip loses.