Update the plugin version.
Don't extract a NetworkManager from a temporary player. Fixes #155

Instead, look up its channel injector directly.
Added more constructors to PacketAdapter.
It is an error to pass an empty type array.
Run onPacketSending() on the main thread if not otherwise stated.

Now onPacketSending() should only be executed on the main thread, 
unless the listener has specified ListenerOption.ASYNC. This option
is off by default, however.

This ensures that older plugins that assume onPacketSending() doesn't
crash the server. They SHOULD use the ASYNC option if possible, as
this explicit synchronization will slow down the STATUS 
protocol somewhat.