Fixed bug #1628: show command returns zero hits when searching a slow target.

Fixed bug #1628: show command returns zero hits when searching a slow target.
The problem was that a client was in Client_Idle case when it was actually
about to perform a search or other operation. The problem was in function
client_prep_connection where a client state was set to CLient_Idle if
connection was already open. This is wrong. The client is not idle: it
is about to perform a search. A new client state is therefore needed:
Client_Continue, which is like Client_Idle but differs in that a client
is considered active. Neither Connecting or Connected are the same stage
because these are states prior to Init Handshake with target.