* Work around broken ftp servers (notably ProFTPd) that can't even follow
RFC 2389, and skip any amount of whitespace before a FEATure response.
The RFC says 'single space' yet ProFTPd puts two.
Noted by DervishD <raul@pleyades.net>.
* Improve formatting of features[] debug dump.
* Invalidate remote directory completion cache if any command which
may change the remote contents completes successfully, including:
del, mdel, ren, mkdir, rmdir, quote, and all upload commands
Patch from Yar Tikhiy <yar@freebsd.org>.