Interactive maps messages review

This pull request was created only for message review purposes. Do not merge it!

Dear ComEng developers: pick red or green background to review the messages and their documentation, please :)

Once you finish review and we address all found issues we'll be able to delete the branch.
Please show this one to a native English speaker. My preference would bee "No maps have been created yet. You can create one by clicking the button above." (with an added call to action) -- the current version feels weird.