* 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
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