[Feature] Accept multi input

[Nemecsek]

From a single output it is possible to connect multiple inputs (one-to-many).
It is not possible to connect multiple outputs to a single input (multi-to-one). If I do it now, a route previously defined is removed.

With this feature it is possible to use barfi to describe real systems (like in my case the schematic of a compressed air system).

[codelion]

Can you not create a new block that has 2 inputs and 1 output and then use that to combine two outputs into one.