Add RF system block diagram components

[rossmeier]

Hi,

thanks for working on this. Circuitikz includes a bunch of features about (mostly RF) system diagram. Do you consider them in scope for this project?
I have started working on some components and utility functions to use them and would be glad to contribute them here if that is desired

[mibmo]

@fenjalien any update on this? :)

[fenjalien]

Yes all circuit components will be considered. Bear in mind that there is a rework on the dev branch that is slowly being worked on.