Detachable Window, Mesh Placement, Improvements and Fixes: Version 1.1

The last couple of weeks, I've been coming back again and again to the AssetPlacer, to not only improve its compatibility with newer Godot versions, but also to add some features that I had on my mind for a while. Here is the complete changelog:

• Added a button to detach the AssetPlacer UI panel
• Implemented placement of Mesh resources, and OBJs imported as Meshes
• Added a button to reset transformed assets
• Fixed compatibility with several other plugins that add custom UI
• Implemented synchronisation of version numbers
• Fixed scene not being marked as dirty when placing assets with the plugin, by using local change history instead of global
• Allow placing assets under a non-Node3D descendent
• Improved error handling when plugin was not installed correctly
• Made use of compiler directives to support different Godot versions in one build
• Added social media links to About page
• Fixed popups not popping up in the screen center
• Fixed a transient window error message (if using Godot 4.1 or above)
• Set initial values properly for custom project settings
• Implemented warning if Terrain3D is detected with no debug collisions enabled
• Fixed an error message when clicking at an empty location in surface placement node

The ability to detach the Window might be a big deal for some of the power users here. Since I've only been working on one screen for a long time now, please let me know if you encounter any issues. 

You can now place Meshes, not just scenes. Why would you want to do that? Because you might want to use MultiMeshInstances. While this does not make use of them directly, I'm working on another tool (which will be Open-Source) that allows you to easily convert placed MeshInstances to a MultiMeshInstance. It'll be a while till it's out, but I'm on it.

If you encounter any bugs with this version, please let me know by creating an issue on Github. I think I have seen at least one error message during my test cycle, but I was not able to reproduce it, so any help is well appreciated.