fdsdat * > fds.dat
	make a data file (with CRC info)

fdsdat -i
	give additional info (very cool)
fdsdat -x
	add filename and filesize and filetype info
fdsdat -i -o
	additional info only, no CRC info
fdsdat -x -o
	extra info only, no CRC info

Filetype info is PRG, CHR, or SND.  SND can be graphics like CHR,
or sound data (which is actually program code or PRG), or save
games.  A number means it is invalid (should be 0, 1, or 2)

FDS Disk seems to have a 'valid' marker, with bytes 49 61 00 00 02.
If these are not set, the Date1 and Date2 are not correct.
Previous version did not print dates if these were not set.  This
version does print dates, but if this is not set, it says "*invalid"
