Modification in static method BoundedArc of IntStart_SearchOnBoundaries:
add exact intersection of canonical curve-surface (when Func is IntPatch_ArcFunction).
1. New testgrid "lowalgos/intss" has been created. It will contain all test cases on geometrical intersection of two surfaces ("intersect" DRAW-command) and two faces ("bopcurves" DRAW-command).
2. New test case for the issue #28493 has been created because the problem is not reproduced on MASTER.
3. Test case (lowalgos/intss/bug24472) for the issue #29501 has been modified in order to check loops of the resulting intersection curves.
