Output ports are drawn backwards

[remram44]

Right now, ports are ordered by sort_key (if set) then the order they appear, with inherited port first, and optional ports appearing last.

However, input ports are drawn from left to right, output ports from right to left.

This is confusing (#976) and it means that if matching ports are entered in the same order in the code, connections will always cross in the pipeline.

Putting them in the right order would make the code slightly more complex (ports would have to be moved when a new one is appended), and would probably mess up current packages.