reverting a change from a few commits ago

Fixes #617
Made E2's overlay width depend on content

Made E2's overlay width depend on the width of the ops and percent text,
and not only the name of the E2.
Made wire overlays only send data when necessary

Wire overlays have always been smart: wire entities would only send
their overlay data to the player who is looking at the wire entity.
Now it's even smarter: wire entities will only send their overlay data
if that data is new to the player looking at it - it'll only send if it
actually changed.