Fix overly sensitive null line check

Slight adjustment of null line check to account for intersection lines of
vertex-to-polygon intersections.

CityDoctorParent/CityDoctorEdge/src/main/java/de/hft/stuttgart/citydoctor2/edge/IntersectPlanarPolygons.java

@@ -154,7 +154,8 @@ public class IntersectPlanarPolygons {
 			List<PolygonPolygonIntersection> intersections, double epsilon) {
 		// check if both polygons have this point in common
 		if (!sharingBothPolygonsThisPoint(p1, p2, point, epsilon)) {
-			PolyLine pPL = new PolyLine(new Coordinate3d(point), new Coordinate3d(point));
+			Coordinate3d realPointCoordinate = new Coordinate3d(point);
+			PolyLine pPL = new PolyLine(realPointCoordinate, realPointCoordinate);
 			PolygonPolygonIntersection pPPI = new PolygonPolygonIntersection(p1, p2, pPL);
 			intersections.add(pPPI);
 		}

CityDoctorParent/CityDoctorEdge/src/main/java/de/hft/stuttgart/citydoctor2/edge/PolyLine.java

@@ -79,7 +79,7 @@ public class PolyLine extends BaseEntity {
 	}
 	
 	public boolean isNullLine() {
-		return isNullLine(0.00);
+		return isNullLine(0.0000001);
 	}
 	
 	
@@ -88,6 +88,13 @@ public class PolyLine extends BaseEntity {
 		if (mpFirst == null || mpLast == null) {
 			return true;
 		}
+		// Check if same point object is start and end
+		if (mpFirst == mpLast){
+			Point3d start = mpFirst.getStart().getPoint();
+			Point3d end = mpLast.getEnd().getPoint();
+			// If start- and endpoint same object: -> not null line, intersection on a vertex
+			if(start == end) return false;
+		}
 		PolyLineSegment currentSegment = mpFirst;
 		double length = 0.00;
 		// Add length of all segments, starting from mpFirst
@@ -108,7 +115,7 @@ public class PolyLine extends BaseEntity {
 			length += segmentLength;
 		}
 		// Check if total length is less than the set tolerance 
-		return length <= tolerance;
+		return length < tolerance;
 		
 		
 	}