Added saving and loading testing to the GridBuilder demo to show how the system can be used to create objects that are permanently in the scene until removed by other means. In testing, I found some improvements that could be made for the sake of Saving / Loading objects. The demo save load are just an example of course but feel free

Changes

• When building placeable objects, the owner of instanced objects will be set to the placed_objects_parent. If you are saving scene data and pack the placed_object_parent in a PackedScene then the instanced objects should be included in the saved resource for save games etc.
• Adjusted build_log.tscn default anchors to the bottom left hand corner of the screen (prevents overlap with placeable_selection_ui,tscn
• Removed tile_collsion_indicator_16x16.tscn This was superseded by rule_check_indicator_16x16.tscn in 3.1. Use that instead

Bug Fixes

• Fixed conflicts where a new level was loaded and tile map needs to be set on the BuildingSystem and GridTargetingSystem again. Call change_level_setup on each system when changing levels to update the system for new levels or loaded game levels.