Support for recording and playing back ATEM macros

[jamesremuscat]

It would be useful to add support for recording and playing back ATEM macros. Sometimes you just don't have enough hands available ;-)

[rjmunro]

It might be better to implement some sort of macros ourselves, so that they can include camera moves and possibly even things like changes to lights and blinds as well as things on the ATEM.

[jamesremuscat]

I think there's value in both, and I'd definitely like to have some fully-fledged macro system at some point!

There's sort of the bare bones of the backend of one in the Scheduler/Event system, which I have used to automate camera movement and switching a couple of times before (you sort of need to write your own Python program for it though).

Supporting ATEM macros is likely to be much quicker to implement and would get us some easy wins, but please do open a new issue for the wider functionality - I'm surprised I haven't opened one already, I've definitely thought about it in the past!