* coherence pass : "main" scenes & co renamed to "level" scenes & co
* auto export now toggled ON by default, but bailing out early if there are no main & lib scenes added
* UI improvement for adding level/lib scenes
* minor cleanups
* all operators, panels etc are now respecting the Blender naming convention
* tweaks & improvements to some of the component operators
* clearer naming for the "advanced" tools for components
* main/library/nothing is now an enumProperty on scenes themselves
* main/library scene listing is a dynamic property of the Blenvy core class instead of CollectionProperties
* this means that removing / renaming scenes using the normal blender workflow automatically changes things for Blenvy as well !
* overhauled & simplified main/library scenes ui accordingly
* same for all the code that needed access to the main/library scenes
* added main/library scene NAMES computed property for convenience
* fixes & experiment to auto export
* added support for "always export" functionality for blueprints & levels
* fixed issues with asset management
* fixed issues with tracker
* more ui improvements (display of the number of assets etc)
* a lot more minor tweaks
* added basic logic, ui, level selector operator etc
* fixed issues with asset dialog
* added experimental "always_export" flags for collections & scenes to enable always
exporting on save for select blueprints & levels (no logic yet, just UI)
* various tweaks & minor experiments
