Default broadcast/listener fix

1. Moved code in ceci-element-base::attached" to ceci-element-base::applyDefaults to be called by component-tray again.
2. Simplified ceci-channel-vis and ceci-channel-menu communication.
3. Added CeciChannelUpdated event from within ceci-element-base for which ceci-channel-* can listen.
Merge pull request #1676 from secretrobotron/t1673

T1673