Clone various parameter lists in livedata

Specifically:

 - On client, clone parameters to sub and methods (so that if they're
   modified outside before the method message is actually sent, before
   the sub params are used for de-duping, or before resending messages
   on reconnect, this doesn't affect what we do)
 - On server, ensure that method bodies mutating their arguments does
   not affect callers of Meteor.call (executing locally)

Fixes #2025.