Wait for odometry message before setting manual datum so that the base and world frame names can be set.

[tgreier]

Issue #820

Add cfg params for default world and baselink frame names in the case where a manual datum is being used.
Otherwise, there is a race condition where if the transform callback runs before the odom callback, then the reference frame names are not set, and the navsat_transform will publish incorrect transforms for cartesian<->world frames.

[ayrton04]

Thanks!

[tgreier]

@ayrton04 How do you manage merging changes from foxy-devel into the master branch or other later branches (such as humble)? Do I do that manually by creating pull requests for each branch?

[ayrton04]

I'd normally cherry-pick them, but as we're deprecating this package soon, it'll be helpful if you'd just open PRs against each. Thanks!