* Fixed crash when an expired connection receives a NAK.
* Increased lower bound on retransmission time to 300ms.
* Removed Linux specific optimization in processing time calculation which
made RPC2 clients assume a server can respond faster than it actually does.
* Fixed the very infrequent SFTP_SendResponse crash again, hopefully for real
this time.
* A non-masqueraded rpc2 client wouldn't send out it's SFTP packets through
the rpc2 socket when talkin to a masqueraded rpc2-server. This broke
backfetches through a firewall.
* Added delayed acks, when an RPC2 operation on the server is taking more than
200ms, an unsolicited RPC2_BUSY is sent back to the client to avoid
unnecessary retransmissions of the request.
* Stricter prototyping for callback functions.
* Fixed the very infrequent SFTP_SendResponse crash.
* Keeping track of current fd offset in sftp to allow non-multirpc transfers
from/to a non-seekable fd (eg. stdout).
09255dc0f9