Setting default channel name and default payload type works OK

Sniffer: only display quotes for string-type payload values
Injector: using unicode() and catching errors

TODO: compatibility with STR legacy payloads; more varied
access to inner payload objects (e.g. push_back)

(for remotely triggered local-IU handlers, in order to let the
RPC call of the remote side succeed as it should).

It is a fast header-only 3rd party lib which does not have
packages on all systems - so I just copied it into include/

It is Herwin's resend fix. Test sources are present but not
enabled during library build (will have to implement test build asap).

ipaaca-python: It's now possible to specify a single string category interest on InputBuffer instantiation.