Knot

A Knot is a nob where two or three pipes meet. The picture shows three examples of knots (from left to right): Knots and pipes together form the equivalent of dendrites in biological neural networks. The dynamic behaviour of knots is different from neurons. They simply pass through all incoming signals.
 * A kink with one incoming and one outgoing pipe
 * A join with two incoming and one outgoing pipe
 * A ramification with one incoming and two outgoing pipes
 * The output voltage of joins is the sum of the two incoming voltages.
 * Ramifications output the incoming voltage on both branches.

Operations on knots:
 * Knots can be created in different ways
 * The Add outgoing dendrite command is available in the context menue of pipes and creates a ramification.
 * In an analogous manner Add incoming dendrite creates a join.
 * Insert knot, also available in the context menue of pipes and creates a kink.
 * Connecting an input line to a pipe creates a ramification
 * Connecting an output line to a pipe creates a join.
 * Knots can be moved like other nobs with the left mouse button.
 * Knots can be selected and deselected like other nobs with corresponding commands in their context menue or with a left double click.
 * Add incoming dendrite/Add outgoing dendrite. These commands are only available for kink knots, as the other types of knots have already the maximum number of connected pipes.
 * Knots can be deleted. The incoming/outgoing pipes are terminated with output/input lines.