Bug fixes and improvements:

• FIX: Children of imported Tile Objects in the hierarchy have the same (physical) layer as their parent.
• FIX: Tile Objects now use the unity:isTrigger custom property.
• IMPROVE: Custom importers can now be automatically invoked upon import with AutoCustomTmxImporterAttribute
• IMPROVE: Settings now supports a "Default Material" field that can be applied to every Tilemap or Sprite that is imported.