Create a tool that allows management of on-map notes.
Notes are designated by an icon on the map, which when
clicked pops up a text editor with the associated content.
New notes are added by clicking in a location that does
not have a note.
The notes dialog will have a 'Delete' button (with
associated confirmation dialog) that will remove the
note from the map.
Changes to a map note must be propagated to all other
Notes are only visible by GM players.