Paths between nodes

[apetkovska]

Add a command for highlighting paths between nodes. The algorithm should start from the output nodes and mark all nodes from the fanin cone until the input nodes. All marked nodes should be assigned a level in order to discover the critical path.

• The user should specify input and output nodes.
• There should be an option for showing all paths, or just the critical paths.
• The user should be able to set a maximum number of paths to show.