Clean up some comments.
Phase one of permissions change.

Privilege checking is moving to the model, and GET is being rationalised as a
means of returning a flattened version of the model tree.
Large-scale GET-change cleanup.

Most of the HTML view now uses flattened GET requests.

There have also been some aesthetic changes to the HTML inspector, and the
loaded item view now works.
Implement DELETE on player states.

This is the same thing as setting the player state to its initial one, which is
:stopped... therefore, it's the same as PUT {state: :stopped}.

O brave new world, That has such features in't!