Added isOpen method.
Implemented functions to world

- Add a new node
- Get a list of open nodes with a certain degree
- Very useful for expanding hypotheses
- Move robot from it's position to a neighboring node
Added node junction methods

Methods to create an edge from one node to another
- Cross to: create crossing edge to node
- Set parent off: Create main edge to node
Completed hypothesis expansion

- Hypothesis contruction
- expansion method complete
- Create unconnected hypothesis first
- Create connected hypothesis after