Unify registration of non-dynamic and dynamic packets, make Spout packets dynamic.

Login, StringMap, and WorldChanged are kept non-dynamic because
they are used in the early login process

Also fix up the handling of the dynamic packets SyncedStringMap
clientside to make sure all the ids are lined up and make sure to call
SyncedStringMap events clientside when updates are received from the
server.

Signed-off-by: zml <zach@zachsthings.com>