[Atlas] Create a tool for removing entities outside the borders of a map

[Itms]

When creating maps, entities can be placed outside the map borders (as reported in #2560 f.e.) if the designer wants.

This is useful for actors and eyecandy, at the visible border of the map, but AIs can also gather automatically from invisible resources, since the territory borders are only graphical when the map is circular.

It would be useful to have a tool that helps map makers removing these entities without having to modify the file by hand.

[trompetin17]

this ticket will be close when #1163 will review and close

[Stan]

Can you make Atlas auto delete objects placed in the fog of war on load ? Or an option to do so ? It happened to me on the scenario that won A16 contest, and I had to edit the XML to find the building that was out of the map.

[Itms]

With #1163 fixed, map makers now will be aware that they are placing entities outside the map.

However, having a tool to remove this kind of entities would be useful indeed, so I'm modifying the ticket :)

[Itms]

In 16149:

Notify map makers when they are placing obstructed entities (overlapping other ones or placed outside the borders of the map). Patch by trompetin17

Fix #1163, refs #2829.