1. Using of the "Closed" flag was unified:
a) this flag is applicable for TopoDS_Wire and TopoDS_Shell only, because these entities may hedge an area in 2D space or a volume in 3D space correspondingly;
b) other types of TopoDS shapes are passing over this flag;
c) changing of this flag should be controlled by high-level algorithms (not BRep_Builder).
2. Implemented verification of the closedness of edges. An edge is closed if and only if its first and last vertices are the same.
3. Test cases were changed according to new behavior.
-Set algorithm flag NotDone if there is a non-degenerated edge with absent 3D curve.
-Check IsDone flag in thrusection command.
-Add test case bugs/modalg_5/bug25568.
Small correction of test case for issue CR25568
Code where DownCast was applied to Handle of the type being not a base class of the target one is revised and (hopefully) corrected.
Code corrected following review remarks
GeomConvert::CurveToBSplineCurve() is called even for b-spline curves to ensure that result is non-periodic
Check for conic is corrected
License statement text corrected; compiler warnings caused by Bison 2.41 disabled for MSVC; a few other compiler warnings on 54-bit Windows eliminated by appropriate type cast
Wrong license statements corrected in several files.
Copyright and license statements added in XSD and GLSL files.
Copyright year updated in some files.
Obsolete documentation files removed from DrawResources.
