Add automatic generation of CMakeLists.txt for msg packages

[jpbusch]

• automatically generate CMakeLists.txt for message packages
  • implemented in asn1ToRosMsg.py
• only add necessary msg files to CMakeLists
• move some access functions for dedicated msg types, to avoid unecessary dependencies

[jpbusch]

Open questions:

• also remove non-build msg files? Would be a 3-liner.
• if removing the msgs, should we also remove the corresponding coding and conversion files?
• generate the CMakeLists.txt with jinja? Disadvantage: required jinja package

[lreiher]

Open questions:

• also remove non-build msg files? Would be a 3-liner.

Yes.

• if removing the msgs, should we also remove the corresponding coding and conversion files?

Conversion doesn't make sense if ROS messages are removed, so should be removed as well. I tend to keep coding though as the ground-truth asn1c output.

• generate the CMakeLists.txt with jinja? Disadvantage: required jinja package

At the current point, I don't think it's necessary. Would replace the multiple f.write calls with a single multi-line text though.

[lreiher]

not yet reviewed