* pmsleep refactor
* Shortened swtmr disabled message
* Added swtimer debug module option to user_modules.h.
* Added comments to user_config.h.
* Fixed error in documentation for node.sleep()
* remove blank sntp.c that got added in during rebase onto dev(6218b92)
* Added #ifdefs around SWTIMER_REG_CB to prevent inclusion of disabled
code
* Add FatFs
* enable BUILD_FATFS for all-module build
* push vfs into rest of firmware
* align maximum filename length
* increase timeout for acmd41 during card initialization
* switch from DOS to Unix path semantics chdrive() is substituted by chdir()
* update to fatfs R.012a incl. patches 1-6
* add callback for rtc provisioning in file
* update docs
* Corrected CPOL/CPHA relationships
* Simplified to remove duplicated code
* Removed comments about when MISO is sampled. ESP seems to sample MISO on same clock edge as when MOSI is set.