> As we have a consensus on REP 116 I have accepted the patch, and released pluginlib 1.7.0 into unstable.

great, I have also marked https://code.ros.org/trac/ros-pkg/ticket/5082 as fixed.

I have one question regarding the version numbers:
How can I check in my code (at compile time) which pluginlib version is available and conditionally use the new functionality?

Dirk