Promote keywords arguments completion.

Mostly when you are completing in a function call, it seem logical that
if keywords are available, they are the ones you are interested in.

IPython/core/completer.py

@@ -190,6 +190,9 b' def completions_sorting_key(word):'
     elif word.startswith('_'):
         prio1 = 1
 
+    if word.endswith('='):
+        prio1 = -1
+
     if word.startswith('%%'):
         # If there's another % in there, this is something else, so leave it alone
         if not "%" in word[2:]: