Added new process-pool runner based on AMPoule (integrated into Evennia).

This allows e.g. utils.utils.run_async to offload long-running functions
to a completely different subprocess entirely, offering real parallelism.

Implementation is still experimental, notably not all objects can be
transferred safely across the wire; also there is no concept of
updating caches yet - so adding an object from the subprocess side
will not be known in the main thread yet (since caches cannot yet tell
the underlying database has changed).

src/utils/ampoule/iampoule.py

@@ -0,0 +1,24 @@
+from zope.interface import Interface
+
+class IStarter(Interface):
+    def startAMPProcess(ampChild, ampParent=None):
+        """
+        @param ampChild: The AMP protocol spoken by the created child.
+        @type ampChild: L{twisted.protocols.amp.AMP}
+
+        @param ampParent: The AMP protocol spoken by the parent.
+        @type ampParent: L{twisted.protocols.amp.AMP}
+        """
+
+    def startPythonProcess(prot, *args):
+        """
+        @param prot: a L{protocol.ProcessProtocol} subclass
+        @type prot: L{protocol.ProcessProtocol}
+
+        @param args: a tuple of arguments that will be passed to the
+                    child process.
+
+        @return: a tuple of the child process and the deferred finished.
+                 finished triggers when the subprocess dies for any reason.
+        """
+