RCL ROS types interface in embedded

[vmayoral]

For now the "ChatMsg" is hardcoded using DDS methods in rcl but it's expetected to create an abstraction that uses rosmsgs.

[vmayoral]

I've been reviewing apps/idl and the code works like a charm generating output .c files that make use of the idl definitions. This will be of great help for us and we will go from ROS msgs -> .idl -> .c files.

Using the code is quite straightforward:

./idlparser -o out.c examples/union.idl

generates out.c that can be used within an embedded application.

./idlparser -o out.c -t examples/union.idl

beside the C types, adding the -t flag produces also a test code in out.c. The code can be indented using make indent (rule defined already in the Makefile).

Since the transformation will be performed in the dev. machine we can probably assume that it's safe to use https://github.com/ros2/rosidl_dds.