POM fiddling.
Use shipped sbt-pom-util.
Entity registration revamp. Specifically:

- You must now specify the class under which to register an entity, rather than
  having the class inferred from the supplied entity object. This avoids
  confusion with regard to registering a Bar as a Foo when Bar extends Foo and
  whatnot. Now: whatever class you pass to register() you must pass to
  invoke(). No magic is performed on your behalf.

- An entity's execution context is reified and returned from register(). The
  main reason for this is to allow that context to be supplied to register()
  when registering a child entity which will share the parent entity's
  execution context. This simplifies things and eliminates the previous
  unnecessary requirement that a keyed could only be child of a keyed and a
  singleton a child of a singleton. Do whatever you like. This also enables one
  to dispatch actions and requests directly to a context (if you have one)
  rather than having to look the context up via Nexus, but this is not expected
  to be a common use case. (I should admit here that when I rewrote Nexus for
  Scala, I eliminated class-based lookup entirely and only use these context
  instances, but Scala and Java encourage different usage patterns).