Fix some busybox annoyances.

Fix some busybox annoyances.

* net/tramp.el (tramp-wrong-passwd-regexp): Add "Timeout, server
not responding." string.
(tramp-open-connection-setup-interactive-shell): Dump stty
settings.  Enable "neveropen" arg for all `tramp-send-command'
calls.  Handle "=" in variable values properly.
(tramp-find-inline-encoding): Raise an error, when no encoding is
found.
(tramp-wait-for-output): Check, whether PROC buffer is available.
Remove spurious " ^H" sequences, sent by busybox.
(tramp-get-ls-command): Suppress coloring, if possible.