Modifications:
Definition closure surface by U and V by distance between isolines on bounds
Comparison to isolines on identity
Implementation of short dump of surface and curves
Change order of comparison
Fix and test script for bug 0023475
Modification of script to restore surface
Modification for correction regression ( UIso and VIso were confused)
Modified test case and test surface for bug 0023475
Internal cache in classes implementing b-spline curves and surface in Geom and Geom2d packages is protected from possible concurrency by mutex (added as a class field in each instance).
