Essential node groups

[BrendanParmer]

Changes

Features

• Node groups from the essentials library are now simply linked by default, rather than automatically generating clutter (both in the generated code and the blend file) (Don't recreate default node groups #178)
  • This is a step forward in general library support
  • By default Blender seems to pack the essential node groups, so the generated ones don't look exactly the same in the UI. For 99% of users they should evaluate the same, for the other 1% please just make a local copy or something. I'm interested in feedback on this, and if there's a better way
    • I've chosen not to implement this with bpy.ops.node.add_group_asset(). I'd like to avoid NodeToPython needing to manage the context, and getting the relative_asset_identifier seems a little painful.

Fixes

• Typo with generated GeometryNodeTree.show_modifier_manage_panel attribute

Other

• Better warning messages
• Separated out bl_info and import statement creation, allowing both add-on and script mode to use the same import statements