nfa-pruning-analysis

the screen_size in which the nodes are placed scales now with the number
of nodes in this function:
size = log_{1.6}(number_of_nodes) * scale
Base 1.6 and 500 as scale was in testing the sweetspot for small graphs
(3 nodes) and bigger graphs (50 nodes).

The placement was changed due to an understanding error.
The methods "nx.springlayout(graph)" gives every node an array of
coordinate from the range of -1 to 1 in the x and y axis.
So the placement was changed to work with this given range.