First FatFs commit

only petSD tested up to now
Merged master
first commit for FatFs on XS-1541
fatfs: better support for different environments
FatFs: XS-1541 works
Merge branch 'master' into fatfs
Merge remote-tracking branch 'nils-eilers/fatfs' into fatfs
Merge master into fatfs
Rearrange fatfs files and directories
Remove old files
Merge branch 'master' into fatfs
Replace CS_HIGH/CS_LOW with inline sdcard_cs(x)
Reduce RTC status to 8 bits
Add a timer with 10ms resolution, let LED timer do this too
Make access to variable used by interrupt atomic
sdcard: timeout and media change
Move fatfs docs from /doc to /docsrc
fstcp is not there, don't try to install it
Update media status without SD CD IRQ, improve sdcard send_cmd debug output
Add card detect pin change IRQ for petSD