Moving BinlogPlayer into its own file.
Merge branch 'master' into resharding
Refactoring binlog_player.

It should be ready to be used inside vttablet now.
Adding a ShardMultiRestore command.

It calls multi-restore on each individual tablet in a shard,
and also populates the SourceShards in the shard record.
Skeleton of a binlog player controller.
Adding intersection methods for KeyRange.
Checkpoint of binlog player work.

Now the player starts correctly. stats are re-registered
after 30 seconds when the player cycles, and that kills
vttablet, need to work on that next.
Merge branch 'master' into resharding
Merge branch 'master' into resharding
Fixing variable export, now test runs forever.
Combining host+port into addr in blp_checkpoint.

They were only used together anyway.
Moving connection logic so it's in the loop.
Adding and registering stats.
Adding states, fixing mutex access.
Merge branch 'master' into resharding

Conflicts:
	go/cmd/vt_binlog_player/vt_binlog_player.go
	go/vt/vttablet/agent.go