Differentiate number of neighbours and number of nodes

[abelsiqueira]

Currently, we use min_neighbours to be the number of neighbours of a point, but also the number of nodes in a graph. Since the number of nodes should be the POI + neighbours, the relation should actually be "num_nodes = min_neighbours + 1".

Possible solutions:

• Find the places where we use min_neighbours when we actually mean num_nodes and update accordingly. The tests, in particular, have a few of these.
• Change the parameter name to min_nodes and update accordingly.