make sure we only perform absolute imports on loading a backend

Fixes #2309
Fix accidental merge
pep8 fixes
made example clearer
 - use OO interface to set tick labels rather than pyplot
 - explicitly set ax2.ylim, rather than relying on auto-scale magic
Merge pull request #2325 from matthew-brett/deal-with-broken-qt4

BF: guard against broken PyQt import
Merge pull request #2316 from vbr/patch-6

Replace the obsolete wx.PySimpleApp
Fix bug in texmanager font-family parsing
Merge pull request #2306 from lpsinger/mollweide_latitude_grid

Mollweide latitude grid
Fix accidental merge
Use macroman rather than ascii to decode SFNT table names
Merge pull request #2307 from mdboom/font-name-decoding

font_manager.py UnicodeDecodeError when starting ipython --pylab
Merge pull request #2345 from mdboom/texmanager-family-crash

texmanager font selection crashes
Add a comment explaning __import__ syntax.
Add paragraph about PDF code of conduct.
Make pylab inline figures work again
Merge pull request #2358 from mdboom/fix-inline-figures

Broken IPython notebook integration
Enable Amazon S3 and fix URL
Merge remote-tracking branch 'upstream/v1.3.x'

Conflicts:
	.travis.yml
	lib/matplotlib/backends/qt4_editor/formlayout.py
Add S3 info
Better axis limits when using shared axes and empty subplots