Add optional array argument to bbs.telnet_gate() and bbs.rlogin_gate()

If an array argument is passed to these methods, the stringified contents of
each array element value will be sent to the remote server after connecting.

This is to support Nelgin's request of sending some strings to a server after
connecting. There's no way to insert pauses between the sent strings or wait
for certain output from the remote - that's beyond this scope/capability.