threadutil: explicitly import get_ident from thread

The python module thread is the low-level module we should avoid to use in favor
of threading. We still need it to support old python because Thread.ident
doesn't exist before python 2.6:

	http://docs.python.org/library/threading.html#threading.Thread.ident

Make it clear we should avoid it.

Reviewed-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/ui/Blinkenlights.py

@@ -18,7 +18,7 @@
 
 from threading import RLock, currentThread
 from offlineimap.ui.UIBase import UIBase
-import thread
+from thread import get_ident	# python < 2.6 support
 
 class BlinkenBase:
     """This is a mix-in class that should be mixed in with either UIBase
@@ -103,7 +103,7 @@ class BlinkenBase:
         UIBase.threadExited(s, thread)
 
     def gettf(s):
-        threadid = thread.get_ident()
+        threadid = get_ident()
         accountname = s.getthreadaccount()
 
         s.tflock.acquire()