reworking Reg to support built-in mask, Reader/Writer interfaces
reworking registers to impl ReaderFrom and WriterTo; to use with SPI later
tests for ReadFrom
update config to match recent changes to reg.R
update addrw to recent reg.R changes
update autoack to recent reg.R changes
update dynpd to recent reg.R changes
update enrxaddr to recent reg.R changes
update feature according to recent reg.R changes
update fifo according to recent reg.R changes
update retrans according to recent reg.R changes
update rfchan according to recent reg.R changes
update rfsetup according to recent reg.R changes
update rpd according to recent reg.R changes
update xaddr to recent reg.R changes
update rxpw to recent reg.R changes
update status to recent reg.R changes
update txobs to recent reg.R changes