Changed mothod name Notification#toBinaryTemplate to Notification#getCompiledNotification.

Then renamed related variable names.
- template -> compiledNotification.
- notificationOrTemplate -> notification.
Also added `isCompiled` member to the compiled notification.
Reduce overhead in Connection#showState, a debug purpose method.
Enable to callback of broadcast to return any false value, e.g. null.

Previously it was only allowed to return `false` to stop the cycle.
Added Connection#bulksend.

Useful to send a variety of notification contents in pull-contents-model.