Created base classes for ObjectGraph and ObjectGraphNode.
Added ObjectGraphEdge + test.
Made ObjectGraphEdge::getDistance() const.
Implemented operator == and != for ObjectGraphEdge.
Removed unused mathutil include from objectgraphedge.cpp.
Some ObjectGraphNode implementations.

- Refactored contsructor which now requires parameters.
- Added std::vector to store its edges.
ObjectGraph now longer inherits std::vector.
Added ObjectGraph::compareTo() stub.
ObjectGraph now stores nodes and edges.
Created ObjectGraph::insertNewNode and ::getNodeCount() + tests.
Added ObjectGraph::insertNewEdge and ::getEdgeCount() + tests.
Added OjbectGraph dtor.
Added ObjectGraphEdge getter for start / end node.
Merge branch 'master' into olga-data-structure

Conflicts:
	test/src/main.cpp
	test/test.pro
Created ObjectGraph::findEdge().
Added ObjectGraph::findNode().
Added PointerCompare class.

Can be used to compare pointers by referencing their targets and calling <.
Added ObjectGraphNode::addEdge() and ::getEdges() and added tests.

cherry-picked... conflicts:
	test/src/main.cpp
	test/test.pro
Implemented ObjectGraphNode::operator<().
ObjecGraph now stores nodes in a set.