* implement draft-ietf-ftpext-mlst-10 commands, especially MLST and MLSD.
we already supported SIZE and MDTM. add the appropriate FEAT output lines.
* migrate a lot of the command code from ftpcmd.y and ftpd.c to cmds.c
* make dataconn(), feat(), lookup(), opts() and sizecmd() public
* modify struct tab so that it has a `flags' instead of `implemented' element,
and remove the `hasopts' element. If flags == 1, the command is implemented.
if flags == 2, the command is implemented and takes options
* add macros ISDOTDIR(x) (is x ".") and ISDOTDOTDIR(x) (is x "..")
* modify lreply() so that lreply(-2, ...) just outputs the given info without
a prefix or trailing \r\n. this saves doing b = printf(); total_* += b;
* enhance statcmd(). still needs work in the LPRT status stuff.
* crank version
a26448af43