Minor changes, implemented fatSet.
Fixes in uninitialized values handling.
Added cross-handle linking functions.
Added stubs for unused FAT32 functions.
Minor changes in FAT32 driver.
Updated mutex handling functions.
Complete refactoring of shell example.
Fixed fsTruncate for FAT32 dirs.
Changed behavior of fsUnlink and fsTruncate for FAT32 directories:
fsTruncate now frees cluster chain or fails when directory not empty;
fsUnlink just removes directory entry and ignores emptiness.
Fixed shell example makefile.
Changed directory structure.