there should be also a demultiplexer. it would be really useful.

Logisim: https://sourceforge.net/projects/circuit/
Logisim repo: https://github.com/lawrancej/logisim

IEC:

ANSI:

My Super Circuit Maker design: https://gist.github.com/anonymous/159df663d4ff24305fdd3d032a2809bb

Pin Map:

Example:

Close-up:

Honestly I'm pretty much done adding gates for now. This can be made yourself in an IC once the fabrication module is done. I'll have a beta release of that very soon.

Doesn't need a separate gate, just ability to swap IO on existing one.