Of particular note this removes the partial SUMH support. This has been
broken as far back as 2018, as we only called add_input() if we were in
the SUMD or SUMD failsafe cases, which meant SUMH didn't work. This
commits to that path, and removes all the 8 bit CRC, SUMH support.
This also refactors a number of things for readability (condensing white
space, simplifying guards around debug code). Many of the debugs could
probably be removed, but this simplifies it.
This was tested against the RCProtocol example test, and everything
there reports a pass.
