Half-done FAT library

This was primarily written for learning purposes, but also when I were
doing some AVR programming and wanted to write a boot loader that could
flash the chip using a MMC on start-up.

Since the MMC was formatted using FAT16/32 (not FAT12 - I didn't have
cards that were that small), I had to write FAT implementation.

Then I continued to add write support for a project whose goal was to
connect an AVR to a GPS chip and to a MMC card, and periodically write
the GPS position (or actually, raw NMEA entries) to the SD card.

Bugs do exist. Maybe nothing works. But if you find any use of it,
you're welcome.

Best regards,
Victor Boivie

(The code was originally written in 2006)