OTR Proxy breaks support of multiply clients.

[Alexandr Akulich]

Hi all.

OtrProxyChannel::Adaptee::connectProxy() at [1] line 170 doesn't
connect to messageSent() signal, which makes ktp client to ignore
messages, sent by other clients. This isn't trivial to fix, because if
we connect to the signal, then we should filter out our own emission
at [1] line 466.

The proxy is involved regardless of settings and plugin enablement and
it is especially annoying, because it affects telegram connection
manager (telepathy-morse), which works fine with any other Telepathy
client, such as Empathy, jolla-messages (Sailfish client) and ktp
without the proxy.

[1] https://quickgit.kde.org/?p=ktp-common-internals.git&a=blob&f=otr-proxy%2FKTpProxy%2Fotr-proxy-channel-adaptee.cpp