Feature request: rns lite, only transport without any cryptography

[LaneaLucy]

The idea behind this is that the main problem factor to port rns to microcontroller for simple repeater is the cryptography dependency. With a extra lite version or a start argument that disables everything other then the transport, That would be much simpler. And you don't need the rest for a simple repeater, which would make it more lightweight. I'm not that much into the rns code, so someone other with more known of the code should be easily be able to make this. If using the start argument method, someone just need to put a if in the right place and maybe override transport mode to true.

Thx