ros2 branch was cleaned up and force-pushed

[rhaschke]

I went through all commits pushed onto the ros2 branch in recent months from PickNik's side and cleaned them up to the standards of this repo. Many of them I moved to the master branch and eventually merged them back into the ros2 branch. Using merging instead of cherry-picking, one can more easily see which commits are on which branch.

Attention: I force-pushed the ros2 branch to the new, cleaned version. Please update your local workspaces, resetting your local ros2 branch: git remote update; git reset --hard origin/ros2.

Only a few commits, whose value I still consider questionable, are left on the ros2 branch. These include:

• #450 (I think a dedicated solver is more suitable in the context of MTC)
• #490 (this info is not displayed anywhere, integrating it into the comment makes more sense - which was realized in #523)

Some others are ros2-specific, for example:

• #496 (only relevant for the ros2 action server)
• #506

For now, I kept the old ros2 branch with name ros2-old. I will delete this branch in a few weeks. The new branch should™ include all functionality of the old one as well as all improvements from the master branch. See here for all differences. To highlight my changes even more, I created a cleanup branch, where individual changes can be seen more easily. In the new ros2 branch, those cleanups are squash-merged into the corresponding main commits, though.

Comparing PickNik's ros2 branch with the old ros2 branch, apart from many missing commits, I noticed larger deviations in ExecuteTaskSolutionCapability. So far, I don't understand, why you, @henningkayser, refactored this code so much. In any case, I think you should consider switching to the new ros2 branch.