Fixed foolscap imports.

As of Foolscap 0.4.3, foolscap introduces a foolscap.api module
that all top-level symbols must be imported from.

Fixes https://bugs.launchpad.net/ipython/+bug/525805

IPython/kernel/enginefc.py

@@ -28,7 +28,10 b' from zope.interface import Interface, implements'
 from twisted.internet.base import DelayedCall
 DelayedCall.debug = True
 
-from foolscap import Referenceable, DeadReferenceError
+try:
+    from foolscap.api import Referenceable, DeadReferenceError
+except ImportError:
+    from foolscap import Referenceable, DeadReferenceError
 from foolscap.referenceable import RemoteReference
 
 from IPython.kernel.pbutil import packageFailure, unpackageFailure

IPython/kernel/fcutil.py

@@ -24,7 +24,10 b' from twisted.internet import reactor, defer'
 from twisted.python import log
 
 import foolscap
-from foolscap import Tub, UnauthenticatedTub
+try:
+    from foolscap.api import Tub, UnauthenticatedTub
+except ImportError:
+    from foolscap import Tub, UnauthenticatedTub
 
 from IPython.config.loader import Config
 from IPython.kernel.configobjfactory import AdaptedConfiguredObjectFactory

IPython/kernel/multiengineclient.py

@@ -22,7 +22,11 b' import warnings'
 from twisted.python import components
 from twisted.python.failure import Failure
 from zope.interface import Interface, implements, Attribute
-from foolscap import DeadReferenceError
+
+try:
+    from foolscap.api import DeadReferenceError
+except ImportError:
+    from foolscap import DeadReferenceError
 
 from IPython.utils.coloransi import TermColors
 

IPython/kernel/multienginefc.py

@@ -24,7 +24,10 b' from zope.interface import Interface, implements'
 from twisted.internet import defer
 from twisted.python import components, failure
 
-from foolscap import Referenceable
+try:
+    from foolscap.api import Referenceable
+except ImportError:
+    from foolscap import Referenceable
 
 from IPython.kernel import error 
 from IPython.kernel import map as Map

IPython/kernel/taskclient.py

@@ -20,7 +20,11 b' __docformat__ = "restructuredtext en"'
 
 from zope.interface import Interface, implements
 from twisted.python import components
-from foolscap import DeadReferenceError
+
+try:
+    from foolscap.api import DeadReferenceError
+except ImportError:
+    from foolscap import DeadReferenceError
 
 from IPython.kernel.twistedutil import blockingCallFromThread
 from IPython.kernel import task, error

IPython/kernel/taskfc.py

@@ -24,7 +24,10 b' from zope.interface import Interface, implements'
 from twisted.internet import defer
 from twisted.python import components
 
-from foolscap import Referenceable
+try:
+    from foolscap.api import Referenceable
+except ImportError:
+    from foolscap import Referenceable
 
 from IPython.kernel import task as taskmodule
 from IPython.kernel.clientinterfaces import (