re-added lines to make sure that `bottom` and `left` are not None in
the case of `log=True`.  If this is not done, there will be type
exceptions.

Issue #1882
simplified logic related to bottom=None and log in `bar`
qt4_editor formlayout now works with colour tuples
Fixed call to path.Path.contains_point from pnpoly. contains_point accepts a list as its first argument.
Request a specific version of Gtk when using gi
fix pstoeps function in backend_ps.py
Merge pull request #1889 from tacaswell/log_bar_regression

Fixed handling of `bar(.., bottom=None, log=True)`
Fixed typos in legend docs.
Merge pull request #2047 from pelson/legend_doc

Fixed typos in legend docs.
On Linux, use the XDG base directory specification for configuration and cache directories
Deprecated the set_colorbar method on a scalar mappable.
backend_gtk: don't hide FileChooserDialog; closes #1530

Hiding the FileChooserDialog was pointless, because a
new one is created each time the Save Figure button is
clicked in the Toolbar.  Hiding seems to have prevented
the widget from being destroyed based on refcount, and this
led to heavy access to the recently-used.xbel file with
every subsequent keystroke.
backend_gtk3: same fix as for backend_gtk, don't hide file chooser
Added an api_changes note about the deprecation of ScalarMappable.set_colorbar
pep8 fixes in animation.py
Merge pull request #2055 from pelson/mappable_colorbar_attribute

Deprecated the set_colorbar method on a scalar mappable.
Add a better error message when IPython can't be found or doesn't have all the right stuff.
Merge pull request #2057 from tacaswell/animation_pep8

pep8 fixes in animation.py
Merge pull request #2017 from drevicko/fix-form-colors

qt4_editor formlayout now works with colour tuples (fixes Issue #1690)
Merge pull request #2053 from mdboom/ipython-directive-error-message

sphinxext.ipython_directive import error.