This work requires the completion of the DGML refactoring in order to get started.

This task is about extending the map creation wizard so that it has a dedicated page for the step of creating the legend/map key.

A preview of the map legend should be made based on the QTextBrowser (in preparation for using the MarbleLegendBrowser). It should be displayed on the left of the page and cover the fully height

On the right the following checkboxes should be added:

[x] Coordinate Grid

[x] Populated Places

[x] Terrain

[x] Places of Interest

Once the user has made the choice the proper dgml gets created that creates those checkboxes in the map key of the Marble application.

In a follow-up task this page should get extended so that the user can tweak/extend the map key interactively using the preview.