statistic helper classes

test-cases
modified grid importance for better trap-detection

tests/grid/TestGridWalk2HeadingControl.cpp

@@ -30,6 +30,7 @@
 
 
 struct MyNode12456012 : public GridPoint, public GridNode {
+	float getWalkImportance() const {return 1;}
 	MyNode12456012() {;}
 	MyNode12456012(const int x, const int y, const int z) : GridPoint(x,y,z) {;}
 };