typegen did not support mqueue's yet (only corba), so I added mqueue to the
set of supported transports.

Since Sylvain is out of office for a long time, and this is not an intrusive
patch, I'll push it to the Orocos toolchain.

What is convenient about using typegen, is that the boost::serialization code
is automatically generated from the existing C++ class or struct. The
generated code also contains the necessary cmake logic to compile it into a
compliant transport plugin.

It also serves as an example to create a very simple transport with
orogen/typegen.

Peter