Add multiple selection for entities.

[pro0digy]

Would be much easier, for example, to select all of those 234 lootcrates created after dismantling a base and delete them with one click.

[budak7273]

A "delete children" context menu option might also be nice in addition to this

[BistroBullet]

No really, this would be so helpful. Imagine clearing all inventories and just starting the game. You could really do a stress test with your factory! This would be so huge! Pls implement this! In the entity tree, just let us select multiple files with Shift or Ctrl and I would be sooooo happy! :D

[budak7273]

This is in progress as part of the rewrite; see 1fd6e86