lib/FatFs: fix -Wcomment in option/syscall.c
io/uart: reorder tx and rx in struct uart for consistency
lib: add fat library candidates
algo/fifo: use nonvolatile fifo ptr in fifo_internal_*
algo/fifo: use const fifo ptr in fifo_{count,free}
lcd/lcd: add lcd_clear
rtc/ds1302: add stub
io/io: add DS1302 spi ss line
io/spi: add params for DS1302 (with implied 3-wire to spi circuit)
io/uart: rename UART_DEBUG to UART_PC