- Don't disconnect the same socket multiple times (once per TDI_SEND IRP cancelled...

 - Don't disconnect the same socket multiple times (once per TDI_SEND IRP cancelled, once per TDI_RECEIVE IRP cancelled, once per TDI_SEND IRP on a closing socket, and once per TDI_RECEIVE IRP on a closing socket)
 - Implement support for graceful socket closure
 - Fix some memory leaks

svn path=/trunk/; revision=43883