0029093: BOP PaveFiller hungs and constantly consumes memory

Method IntWalk_PWalking::ExtendLineInCommonZone(...) now is not called if the already found intersection point is on surface boundary.
As result, the intersection line going along any boundary will never be extended. It is appropriate for high-level OCCT-algorithm because they will take the boundary (not computed line) as intersection result.

tests/perf/modalg/bug29093

@@ -0,0 +1,30 @@
+puts "========"
+puts "0029093: BOP PaveFiller hungs and constantly consumes memory"
+puts "========"
+puts ""
+
+bclearobjects;
+bcleartools;
+
+restore [locate_data_file bug29093.brep] a
+
+explode a So
+baddobjects a_7
+baddtools a_9
+
+dchrono cr restart
+
+bfillds
+bbuild result
+
+dchrono cr stop counter bbuild
+
+checkshape result
+checkprops result -s 1329680 -v 34507100
+checknbshapes result -vertex 5 -edge 13 -wire 9 -face 9 -shell 3 -solid 3 
+
+smallview
+donly result
+fit
+
+checkview -display result -2d -path ${imagedir}/${test_image}.png