Build 0.8.17.7284 - Full body Avatar anchor improvements

- Added ability to restore user position/rotation when exiting AvatarAnchor
-- Can either restore original transform (relative to the anchor (default) or global) or use another object as reference.
- Added AllowedUrlHosts to the config for headless client, which allows specifying which hosts can be contacted by LogiX HTTP requests (requested by @Anomalous )


- Added robust file delete/move routines to local asset import - this fixes some background exceptions (e.g. when generating thumbnails, importing assets and such)
- Fixed exception when destroying AvatarAnchor (this fixes not being able to remove any objects with them on, reported by @Jazneo )
- Added a exception guard to prevent any errors in OnDestroying events from destroying/deleting the object/component
- Fixed exceptions in head fixing when some of the objects are missing, causing the IK to stop functioning (reported by @Shifty , @RaccoonRezillo and others)
- Fixed exceptions in QuantityTextEditorParser when the default unit is null (discovered in log from @Shifty )
- Fixed AvatarAnchor breaking when there are uncleaned or removed dummy object slots
- Fixed having slight vertical rotation when equipping full body avatars
- Fixed the legs twisting when lying horizontally with full body setup (due to pelvis forward pointing upwards, reported by @KylieSour and @Dani☆ )
- Fixed legs randomly twisting even when standing upright (reported by
@Groxxy and @KylieSour )
- Fixed user being incorrectly rotated when entering avatar anchor using hips as rotation node and using hips Vive tracker
- Fixed HeadFacingRotation not rotating the user correctly when assigned
- Tweaked humanoid rig detection - it should now work for certain rigs without shoulders (based on report from @Willowmoon8 )
- Fixed being able to jump into another avatar in the world when anchored, breaking the anchor (found by @Aegis_Wolf )