Fix use animation breaking for 1.8 viewers when status updates

[Term4]

Redoing this properly from the correct branch of my fork (sorry)

Problemo

When a 1.8 client is a viewer of another player using an item (eat, drawing a bow, blocking a sword), the use animation stops when the watched player sneaks. It doesn't rrestart
until playerr restarts using the item.

Reproduction

1. 1.8 client connects with ViaRewind to a 1.9+ server.
2. Player A starts a use item animation.
3. Player A sneaks while still using the item.
4. The animation stops on the 1.8 viewer's screen and stays gone until A stops and
   restarts the item use.

Fix

Track hand-active per entity in EntityTracker1_9

Manually verified with a 1.8 client through ViaRewind (same test as reproduction now passes)

[Term4]

beaness: "Probably fixes #520"