- solidify/face.h (z0_scale, fx_to_angle, fy_to_angle, fx_from_angle,
fy_from_angle): correct for z vs. xy scale differences
- solidify/overlap.c (merge_matrix): correct z0 shrinkage for z vs. xy
scale differences
- solidify/face.h (struct face), solidify/face.c (read_file): keep the mesh's
maximum Z size in sz, similar to sx and sy
- solidify/povray.c (povray_face): use f->sz insead of calculating it