Add a layer for reporting feedback

[lyret]

In a FB thread its been reported that a layer on the placement map for reporting sleep quality after the event could be useful.

https://www.facebook.com/groups/theborderland/posts/8429392770413415/

I suggest that any implementation to facilitate this should be made a simple as possible.

One possibility could be a "comment" mode seperated from "edit" mode that allows markers to be placed, the markers should be of the types "sound report", "damage", "water", "smell" or "moop" and contain small textual comments. This could also make the map usable for moop sweeping etc.