Added line segment hit testing feature.
Tried to make GraphEdges not intersect each other.

But they seems not working appropriately.
Separated intersection test logic into static function in GraphEdge.cpp.
Added explicit line tests, which revealed a bug in intersectTest().

The GraphEdges hit testing feature seems yet bugging.
Fixed the scale for line segment test.

It seems the logic is correct now.
Erased test codes for intersectTest() verification.

The codes accomplished their purpose and no longer needed.
Accumulated Vehicle's moving and jammed steps to measure how much traffic
is jamming.

The step count are printed in the console.