Register config + behavior keymap

[Mattias]

Hi!

I noticed 2 things which would be nice to have in the config.

• A config to chose the register where to store the yank inside.
• And would it also be possible to, for example, have a keybind where it's automatically the yank behavior and one where it is the insert_below behavior?

Cheers!

[rareitems]

Added it in 37739d2