* bumped up Bevy version to v0.14 !
* fixed (albeit in a clunky way) issues with sub blueprint detection
* improved error message for missing material library
* added HideUntilReady component & logic, to hide 'in-spawning' blueprint instances until they are ready
* "add-to-world" is now only trigerred for blueprint instances that have no parents (avoid footgun)
* minor cleanups & tweaks
* added test component with Vec3 to double check for issues
* updated test blend file to include the component above + added a light to the test spawnable blueprint
to check for "light flashes" (aka indirectly testing "HideUntilReady")
* added additional test "upgreadeable components"
* added test "buggy" hierarchies: blueprint instances as children of empties and blueprint
instances as children of other blueprint instance
* more materials
* testing cases for various levels of nesting/ targets for components
* reorganized objects in 3d scene for more clarity
* changed camera view for more clarity
* added background color & filmic
