huge commit

- worked on about everything
- grid walker using plugable modules
- wifi models
- new distributions
- worked on geometric data-structures
- added typesafe timestamps
- worked on grid-building
- added sensor-classes
- added sensor analysis (step-detection, turn-detection)
- offline data reader
- many test-cases

grid/factory/v2/Stairs.h

@@ -233,7 +233,8 @@ public:
 
 			// no matching node found -> add a new one to the grid
 			if (iNode.idx == -1) {
-				iNode.idx = grid.add(iNode.node);
+				const T* n2 = grid.getNodePtrFor(GridPoint(iNode.node.x_cm, iNode.node.y_cm, iNode.node.z_cm));
+				iNode.idx = (n2) ? (n2->getIdx()) : (grid.add(iNode.node));
 			}
 
 			// add semantic information