rflib: Generate RFProtocolFactory code

Since this code depends on the types generated by msgen.py, it seemed appropriate to have msgen create the boilerplate for these classes. I also included a rename of rfprotocolfactory to match the rest of the RFP files in rflib/ipc.

The functionality of RouteFlow itself should not change after this patch -- just the code generator.

Signed-off-by: Joe Stringer <joestringernz@gmail.com>