Add aep and sureware implementations and clean up some error reasons

that were never part of the engine framework.

The aep and sureware implementations are taken directly from 0.9.6c
[engine] and have been modified to fit the newer engine framework and
to be possible to build shared libraries of.

The aep implementation has gone through quite a bunch of tests and is
cleaned up (there were some misunderstandings in it about how to use
locks).

The sureware hasn't been tested at all in this incarnation and is
basically a quick hack to get it to compile properly.