rand_nick: pass NICKLEN instead of using sizeof()
insert NULL terminator in generated NICKs
Generate a random nickname if needed

The PRNG is seeded with time(null), so N simultaneous connections will
retry, at worst, N times to generate a new nickname. This probably isn't
the best solution, but it works for now with a low volume of users and
low chances of conflict.

The mangpage has also been re-ordered so that the required arguments
appear first.
close socket before exit on error
adjust error messages
detect error on socket reads
accept pack on empty response
more error checking
print newline after download finishes

the newline was removed by a previous commit
simplify README
exit on nickname errors

temporary solution, should probably handle errors by
generating a new nickname
output filename before download
idk how this was in here for so long
change noconfirm option to something sensible
check for errors on strto conversions
add option to disable confirmation before download
add DCC struct to hold parameters before downloading

this will allow asking for confirmation from the user
and optionally changing the filename before the download starts
simplify manpage
fix missing semicolon

i blame golang