* feat(multiple blend files): added example of multi blend file workflow
* feat(tools/auto_export):
* added collection_instances_combine_mode superseeds & replaces "export nested blueprints", with a lot more flexibilty
* added preferences & ui settings
* added (optional) use of marked assets as replacement for "autoExport" collection flag
* added correct cleaning up of temporary sub_collections
* feat(tools/auto_export): change detection added for material changes
* feat(tools/auto_export): blueprints now also use the "combine" settings for nested collections
* feat(tools/auto_export): added correct cleanup of data when removing hollow scenes, so that there is no orphan data left behind
* feat(tools/auto_export): changes to nested collections are now triggering change detection of root
(exportable collections)
* feat(tools/auto_export): now actually useful tracebacks using traceback.format_exc()
* various minor fixes, cleanups & UI description improvements
* docs(README): updated & fleshed out docs
* closes#87
* closes#86
* closes#85
* closes#79
* closes#61
* closes#68
* closes#41