Upcoming API break in urdfdom

[clalancette]

@mikeferguson

Initially I thought I was using those APIs - but looking at it - I guess I’m indirectly using TinyXML through urdfdom in robot_calibration (released into Humble, not yet in Iron/Rolling).

I see, thanks for the feedback.

@mikeferguson

So yeah, I should probably do a proper CMake thing and also update to TinyXML.

But yeah, it seems like that is the right fix.

Given that I haven’t heard any other feedback about this, I’m going to go ahead with this merge, API break, and release of version 4.0.0 of urdfdom today. Then we can finally remove TinyXML from ROS 2.