…rocessing, buffering for graceful handling across timeouts.

Remove skip filter parameter from method signatures, now technically defunct as all requests through get_binary_packet incorporate the same timeout during blocking IO calls.
Introduce InvalidPacketLength exception and employ to detect OpenSSL 0.9.8e flaw at higher logical level than binary packet processing.
Removing case logic in binary packet filtering for channel message types, made extraneous by use of get_channel_packet, and possibly leading to discarded data packets.
Reset connection properties during disconnect. Rework callers of reset_connection to use disconnect_helper.
Bugfix for no encyrption algorithms negotiated with server.

…_channel_filter