+ corners: list of vertices that should be used as quadrangle corners.
+ The parameter can be useful for faces with more than four vertices,
+ since in some cases Quadrangle Mapping algorithm chooses corner vertices
+ differently than it is desired.
+ A hypothesis can be global and define corners for all CAD faces that
+ require it, but be sure that each specified vertex is a corner in all
+ faces the hypothesis will be applied to.