- restored Replace property panel

- bugfix for cylinder frame in Fit Primitive

- added Height Field mode to Fit Primitive

- added resolution control to Fit Primitive

- added experimental Optimize Mesh tool. This tool tries to shift around the vertices so that upper and lower bounds on the internal triangle angles are enforced. This is important for finite-element simulations, as high-aspect-ratio triangles in the input surface mesh lead to problems in the volumetric tetrahedral mesh.