Save template info in new maps

When a new map is created from a template, its version is reset to 0.

It would be useful to access some read-only information about the original template from which the new map has been created. The originating template name, version and date could be shown in the Statistics tab of the Map Info, helping to keep track of maps that are created from templates that may be periodically updated.

This could be done by saving the name, version and date within the template itself, each time it is saved. This info would then be available in all maps created from it.