en@system: kmdl update

- Added `status` and `address` to the set of predefined classes.
- Added a nonce to `handle` for verifying the referenced object is
  still the same. This is mainly for when the object is on another node.
  It also prevents forging of a handle somewhat.

en@site: merge with

- Merged the site with and moved there.
- The previous site is deleted.
- The domain will be removed.

en@kmdl: update text

- Merged .desc and .data back into just .data.
- Defined a general item alias.
- Simplified some things.