Introduce a new variant for nodes, in order to keep track of
the antecedent of a pressure regulation relation between two nodes.

Introduce a new variant for edge gadgets, the pressure regulator.
Move some helper code in dedicated folders.
Finish to implement a very first instable version with
all cables wired to support pressure regulator gadgets on edges.
Fix some little thing in order to test the code against the new
pressure regulator gadget. Found some problems with Kagishitsu network.
Refactor little pieces and fix a non-ortodox way of building a
substitution for edges when a node with load gadget gets associated
a negative pressure.
Add a new version of big network for integration where we
introduce some pressure regulator edges.
Make some attempts to handle edge case of pressure regulation
where pressure at antecedent is less than pressure at consequent.
Implement anomalies detection for edges in pressure regulation relation.
Fix two classes that contain swapped code by mistake.
Add a simple network per pressure regulation inversions.
Write a network specification to exploit pressure inversions on
edge with pressure regulation gadget.
Important fix.
Advance version number scheme to include pressure regulator gadget.