Merge pull request matplotlib#3372 from ericdill/qt4compat

DOC: Fixed the wording of the qt4_compat.py deprecation warning

Author: tacaswell

lib/matplotlib/backends/qt4_compat.py

@@ -1,7 +1,7 @@
 import warnings
 from matplotlib.cbook import mplDeprecation
 _warn_str = ("This module has been deprecated in 1.4 in favor "
-             "matplotlib.backends.qt_compat\n"
+             "of matplotlib.backends.qt_compat\n"
              "This module will be removed in 1.5, please update "
              "your imports.")
 # bulk-imports because we are pretending that file is this file