* begin adding sd.Card refactor
* CSD logic shared between V1 and V2
* failing CRC7 implementation
* passing tests
* rename commands
* implement waitToken
* add status string method
* no crc errors in status; closing the gap?
* add config baud increase docs
* remove some of API
* still working on consolidation of init
* fully comply
* add prints
* remove prints
* remove unused API
* add BlockDevice
* implement Card interface
* rename EraseBlocks to EraseSectors
* add blkIdxer
* working BlockDevice
* delete rustref.go; add readme to sd
* add sd/README.md
* sd: backtrack on EraseSectors, stick to block nomenclature
* remove remnants of sector size
* fix examples/sd/main.go
* add documentation, smoke test and fix a couple bugs
Pat Whittingslow