Preparing for Melodic sync 2020-01-10

Currently Melodic has 16 known regressions and 111 packages ready to sync. The known regressions all stem from a single problem, and I’ll open a PR shortly to revert octomap to an older version to fix those regressions. Besides that, I plan on holding packages starting today, Jan. 10, with a sync next week.

Please comment here if there are any outstanding issues I should know about before performing the sync.

This sync is out.