Make Axes.stem take at least one argument.

When it takes only one, the abscissae default to np.arange(len(y))
Add axes.stem call signature test
Update CHANGELOG with axes.stem change
Fix positional argument parsing
Make stem catch explicit Exception classes
inverting an axis shouldn't affect the autoscaling setting
Renamed all instances of variables named "long" to "lon" to avoid clobbering by 2to3
Remove NO_DEPRECATED flag -- this was accidentally committed.
Added a test for #1553
Remove redundant ob_refcnt's that cause crashes when built in DEBUG mode.
Fixed blitting in Gtk3Agg backend to redraw only area defined by bbox (#1575)
Merge pull request #1578 from spinnau/fix_1575

Fixed blitting in Gtk3Agg backend
Mac OS X 10.5 needs an autoreleasepool here to avoid memory leaks. Newer versions of Mac OS X do not, but it doesn't hurt to have one anyway.
Merge pull request #1579 from joferkington/fix-custom_projection_example

Updated custom_projection_example.py to work with v1.2 and newer
Fix #1583: Crash with text.usetex=True and plt.annotate -- usetex bounding boxes are all NaNs when text is empty.
Fix: positional argument specifiers are required by Python 2.6
Fix: positional argument specifiers are required by Python 2.6
Fix: positional argument specifiers are required by Python 2.6
Fix: positional argument specifiers are required by Python 2.6
Fix: positional argument specifiers are required by Python 2.6