Migrate AMI actions to objects instead of procedures

[rostgaard]

To make the AMI.Action subsystem less rigid, we need to move the existing structure to a new OO-ish structure.

This accommodates a few extra changes

• AMI.Client should be in charge of subscribing for a response
• Each action does not need to know about the client.

[rostgaard]

Every 1.6 action is now outlined in specs, and now needs a proper body.

[rostgaard]

No, one apparently uses the old procedures anymore. I've tagged them as obsolescent and they will be removed soon(tm).