Fixed rmdir operation with recursion on non-existent directory

[Marv-CZ]

When you call rmdir() with recursive=true on a non-existent directory it causes:

TypeError: Cannot read property '0' of undefined
at deleteNextEntry (/opt/noderedftp/lib/node_modules/node-red/nodes/extra/ftp/node_modules/@icetee/ftp/lib/connection.js:808:21)
at /opt/noderedftp/lib/node_modules/node-red/nodes/extra/ftp/node_modules/@icetee/ftp/lib/connection.js:830:5
at final (/opt/noderedftp/lib/node_modules/node-red/nodes/extra/ftp/node_modules/@icetee/ftp/lib/connection.js:515:11)
at Object.cb (/opt/noderedftp/lib/node_modules/node-red/nodes/extra/ftp/node_modules/@icetee/ftp/lib/connection.js:552:11)

rmdir() calls list() which returns "No such file or directory" string instead a error and rmdir() tries to use it as a dir item.

I have replaced list() with listSafe() which is able to return the error, but it has bug too. It doesn't test missing optional arguments. So this patch also solves this issue.

[Marv-CZ]

I found out it's not general problem, but only ftpd server from busybox which I used for testing.

[Marv-CZ]

For non-existent dirname:

BusyBox ftpd
LIST dirname returns data "dirname: No such file or directory" and "226 Transfer complete"
list('dirname', cb) returns [ 'dirname: No such file or directory' ]
rmdir('dirname', true, cb) produces TypeError

Pure-FTPD
LIST dirname returns empty data and "226 0 matches total"
list('dirname', cb) returns []
rmdir('dirname', true, cb) returns error

ProFTPD
LIST dirname returns "450 dirname: No such file or directory"
list('dirname', cb) returns error with message "dirname: No such file or directory"
rmdir('dirname', true, cb) returns error