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/util.py

@@ -0,0 +1,46 @@
+"""
+some utilities
+"""
+import os
+import sys
+import __main__
+
+from twisted.python.filepath import FilePath
+from twisted.python.reflect import namedAny
+# from twisted.python.modules import theSystemPath
+
+def findPackagePath(modulePath):
+    """
+    Try to find the sys.path entry from a modulePath object, simultaneously
+    computing the module name of the targetted file.
+    """
+    p = modulePath
+    l = [p.basename().split(".")[0]]
+    while p.parent() != p:
+        for extension in ['py', 'pyc', 'pyo', 'pyd', 'dll']:
+            sib = p.sibling("__init__."+extension)
+            if sib.exists():
+                p = p.parent()
+                l.insert(0, p.basename())
+                break
+        else:
+            return p.parent(), '.'.join(l)
+
+
+def mainpoint(function):
+    """
+    Decorator which declares a function to be an object's mainpoint.
+    """
+    if function.__module__ == '__main__':
+        # OK time to run a function
+        p = FilePath(__main__.__file__)
+        p, mn = findPackagePath(p)
+        pname = p.path
+        if pname not in map(os.path.abspath, sys.path):
+            sys.path.insert(0, pname)
+            # Maybe remove the module's path?
+        exitcode = namedAny(mn+'.'+function.__name__)(sys.argv)
+        if exitcode is None:
+            exitcode = 0
+        sys.exit(exitcode)
+    return function