Bootloader rework and a lot of comments added
Basic syscall handler implementation
read_sector() and write sector() implemented
Functions read and write to disk sector refactored
sysfun.c
	read_sector(arg1, arg2, NULL, NULL) and
	write_sector(arg1, arg2, NULL, NULL) are now
	access_sector(arg1, arg2, RW, NULL)
utils.asm
	_read_sector_raw and
	_write_sector_raw are now
	_access_sector_raw

	unsued code removed
External tools for sfs and first sketches in kernel
  - sfscreate	added
  - sfsadd	added
  - in kernel equivalent prototyped if fs.c
Merge branch 'sdm' into mox