#3 Manual graph pruning

[Brendan Cleary]

We wish to implement a use case by which the user can
by right clicking on a node select to remove that node
(and its children if it’s a root of a sub graph) from
the graph. This would most likely require that we
identify and remove the node from the under lying data
model and update the graph by re applying the graph
layout algorithm to the modified data model.