1. There has been implemented calculation of all possible types of continuity for shared edges:
* G1 is set if tangential planes are the same for connected faces in each control points through the edge;
* C1 is set in addition to G1 conditions if derivatives, orthogonal to the edge on each face, are equal vectors;
* G2 is set in addition to G1 if the centers of principal curvatures are the same for connected faces in each control points through the edge;
* C2 is set in addition to C1 and G2 if directions of principal curvatures are equal;
* CN continuity is set only if both connected faces are based on elementary surfaces (the conditions for this case are similar to C2 continuity).
2. ShapeFix::EncodeRegularity() is merged into BRepLib::EncodeRegularity().
3. Implemented several test cases to check correct handling of regularity.
4. Fix incorrect usage of BRepLib::EncodeRegularity() in BRepBuilderAPI_Sewing.
5. Implement a method for calculation of regularity on the given list of edges.
6. Documentation updates
Method BRepLib::EncodeRegularity() is improved to set regularity GeomAbs_CN for edges lying on the same-domain surfaces (where derivatives on both surfaces are equal in all points).
DRAW command getedgeregularity is added to query regularity of the edge on specified faces.
DRAW command edgeregul is removed (this functionality is provided by command encoderegularity).
Added tests: bugs modalg_6 bug27272, bug27383_1, bug27383_2
Correction of shape name in test case for issue CR27272
