Spurious Events From MessagingClient in msgtools.js

[mosminerCP]

My trick of delegating to a disconnected DOM event isn't quite perfect. It appears Chrome shoots out spurious events on the disconnected div tag which is resulting in unexpected messages being sent to the client.

Need to implement our own listener list and management to get around it since Safari won't allow direct derivation from EventTarget.

[mosminerCP]

Went with a less elegant roll our own EventTarget solution.