- use setOriginalsFromValues function right after elements had changed and
**only** with those elements
- add checkbox handling to setOriginalsFromValues to match hasChanged
- apply hasChanged after value is set to refresh originals after saving
- change parts that already set 'original' attribute manually
This was sort-of broken, because original attr never worked as intended.
Also fix possible OOM for large WebUI images, since sending full config each time means that we need more memory to buffer and parse it.