Support for repeating subcircuits/channels/rooms/groups (lp:#1521062)

Original report created by alex haynes (aheinous)

It is very common for circuits to have the same subcircuit repeated
multiple times. Currently you have to cut and paste the circuit multiple
times in Eeschema and then layout each instance of the subcircuit one at a
time in Pcbnew. I am aware of the klonor-kicad scripts (
https://www.youtube.com/watch?v=mChTfL746Fs ) but they really don't work
very well if you want to make changes to the schematic and then propagate
them forward to the PCB. If had the ability to have a subcircuit
automatically repeated multiple times in the schematic editor and then had
the ability to copy the layout to the different instances  of the circuit
in Pcbnew  that would be a huge time saver. It would also result in nicer
looking layouts since it would get copied exactly right. For me personally
this is the biggest problem I have with KiCad, which I think is generally
pretty great. It is weird to me that this is not anywhere on the
development roadmap.

Original tags: eeschema feature.request pcbnew

Note: this issue also covers being able to group/ungroup items (without the added logic of rooms/channels) just for the purposes of moving them as a single unit.