Changed signature of str_split_... to return int (num of new tokens)

ROS backend depended on a mosquitto function, a stray copy-paste line ...

Unreliable delivery during handshake phase persists.

The major caveat for ROS is potential message loss right
after a Publisher is advertised. tcp_nodelay has been set
in the Subscribers and latching in the Publishers (resending
the last message on demand to late Subscribers).
These are not completely airtight fixes, though.

The C++ parser is very minimal and ignores section markers (in our
case there isn't really any need for different sections anyway).
Python expects one section [ipaaca] - the format of the files
is otherwise standard ConfigParser / ini:

[ipaaca]

transport.mqtt.host=localhost
transport.mqtt.port=1883

backend=ros

You can override any of those using an environment variable
e.g. IPAACA_TRANSPORT_MQTT_HOST for transport.mqtt.host

Requires some preparations of the lib dependencies;
prepackaged compiled ipaaca libs ought to be provided.

Some reusable refactoring into generic BackEnd possible