Otherwise clean up the includes. Don't include anything included by
param.h. Do include systm.h and cons.h to avoid satisfy -Wimplicit.
Don't include console.h or use NOKEY because these are for syscons
and we use generic consoles.
Don't follow null pointer for command "ls -lrt" - don't allow extra
args but do allow trailing blanks.
Check for invalid device numbers. strtol() failures are now checked
for in all cases, but not carefully enough. We should check for
trailing junk, allow any base in all cases (just like config) and
handle signs better . (Use strtoul not strtol and cast by assignment
to the correct type - always an integral type, PARM_ADDR is bogus.
Hex numbers > 0x7fffffff can't be entered now. 0xffffffff has to
be entered as -1.)