lord_helmet

prepare to release 2.0.0!

killing py3 bugs as we find them.
also, since SDCC v3.5.0 is the last version to correctly build RfCat firmware (working on it @meeas!), inserted a Makefile catch that will keep you from installing dorked firmware with later versions of SDCC.
moved vstruct inside rflib, so as not to conflict with the real thing when people have Vivisect and/or some other Vstruct using tool installed.

same firmware as 1.9.2, look there for precompiled binaries.