Simplified map cloning

I find map cloning rules to be confusing for no reason that I understand, so I would like to propose simpler cloning rules:

• Make all maps with the same grid location and zoom level automatically just be clones of eachother.
• If a map is a locator map then it shows all the markers, otherwise it doesn't.
• Keep "copy map" on the cartography table since it's handy to set a new map to the same grid location and zoom level as an existing one, and the only way to copy a map if you're not in the map's area any more.

And that's it.

Especially this gets rid of the current behavior when multiple cloned maps have their zoom levels increased, and they aren't clones any more, which is one of a few things that I find confusing and un-fun.

Thanks!