Improve findEdgeCovers #21
Description
So far, findEdgeCovers go through ALL edges of a graph looking for edge covers. By exploring all edges we find the same solutions several times, and then we filter them. That is not efficient.
By going through the different nodes in order, checking which combinations of its edges could be added in future edge covers we could save time. We would go to node A and try all combinations of a single edge, 2 edges, and so on till the total number of edges. We would also consider the option of getting no more edges from a node if this has already been covered.
Apart from speed, this method would allow us to introduce the new constraints we use, for example, to produce noon states. The new post-selection rules can be applied faster by doing this than by working with combinations_with_replacement and then filtering tons of wrong solutions.