Allow user to choose Directionality

[Convincible]

Add option for the graph to be plotted:

1. Left to right (as at present)
2. Right to left
3. Top to bottom

https://www.openownership.org/visualisation/core/directionality/

[Lathrisk]

~~I have added a parameter that allows this to be controlled through the scripts. We would need to add controls to the demo and instructions on how to use this in user applications to complete this work.~~

I tested the added parameters and they effectively break the graph due to the way in which the custom edges are calculated. This would be fixable but is definitely non-trivial.