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This is a light-weight c++ only geometry extension to enable migration of information that was stored within
the Part WB and should be migrated to another WB (for example Sketcher WB)
It is designed so that a single extension can migrate different types of data (current and future).
When new data needs to be migrated, first a new enum bit is to be added to the class enum and new data members are to
be added to store the information within GeometryMigrationExtension class.
In the Restore() function restoring the data to be migrated, a GeometryMigrationExtension extension is added to the
geometry to be migrated with the data information and the corresponding enum bit set.
In the object to receive the migration data, onDocumentRestored() it is checked whether an extension of type
GeometryMigrationExtension is present, if yes, it is checked whether a bit used for migration is set and, if yes,
the data is retrieved and the GeometryMigrationExtension extension (preferably) removed from the Geometry object.
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Encapsulate Part::Geometry data member copy process in a single function (copyNonTag).
Part::Geometry derived classes need not know the specifics of the data member of Part::Geometry.
Change the delegation of the copy of extensions from clone() to copyNonTag. Because clone() relies on
copy() and now copy() of Part::Geometry data member relies on copyNonTag(), there is no actual change
to the clone() functionality, but the copy() funcionality gains the copy of the extensions via copyNonTag().
When using gcc 10 and PyCXX 7.1.4 on Fedora there is an error because the conversion from size_t to Py_ssize_t is ambiguous
See https://forum.freecadweb.org/viewtopic.php?f=4&t=52502
The class Py::Tuple is also incorrectly used here and causes a memory leak
For certain OCCT versions in the file ShapeUpgrade_UnifyDomain a method of the class Precision is used but Precision.hxx is not included which can lead to a build failure.
+ rename getCurve2dFromGeom2d to makeFromCurve2d
+ add function makeFromCurve and makeFromTrimmedCurve like makeFromSurface
+ implement OffsetCurve.BasisCurve
+ fix memory leak in BRepOffsetAPI_MakePipeShellPy
