Fix all tabs

According to our coding guidelines tabs are not allowed and should
be substituted with the required amount of spaces. This tries to
do so.

Switch to new FairMQMessage::Copy() semantics

Switch to new FairMQMessage::Copy() semantics

Fix a few warnings from Xcode 9.2 clang

add boost signals library as a dependency

add boost signals library as a dependency

Interaction record sampler class + its test

Revamp documentation

This revamps a bit the documentation, making it more coherent with
the current implementation and tries to be more geared towards
implementing your own workflow rather of a description of the
implementation details.

Revamp documentation

This revamps a bit the documentation, making it more coherent with
the current implementation and tries to be more geared towards
implementing your own workflow rather of a description of the
implementation details.

bugfix: set payload serialization method

serialization method has to be set to NONE in order to be consistent
with the check in DataRefUtils::as<>