Closes 1752. Patch3DCollection can now be empty.

Also improved the Patch3DCollection constructor.
Closes #1079. Allow iterables for Line3DCollection
Update the coding guidelines wrt to docstrings and MEP10
Merge pull request #2162 from WeatherGod/mplot3d/empty_patch3dcollection

[SPRINT] Closes #1752. Patch3DCollection can now be empty.
Splitted the axes module into smaller chunks
FIX process_plot_format is not in the axes module anymore
ENH now can run the tests on triangulation without the test runner
Documented the changes
DOC the refactoring of the axes module is now mentionned in the API_changes.rst file
ENH shuffled around some extra methods between Axes and _AxesBase
FIX importing _string_to_bool from the wrong module
Added missing '#'; when starting ipython, I was getting the following message:
Bad key "text.hinting_factor" on line 184 in
/home/marianne/.matplotlib/matplotlibrc.
You probably need to get an updated matplotlibrc file from
http://matplotlib.sf.net/_static/matplotlibrc or from the matplotlib source
distribution
Merge pull request #2173 from mdboom/docstring-coding-guidelines

[Sprint] Update coding guidelines wrt documentation
Merge pull request #2172 from WeatherGod/mplot3d/iter_collections

[SPRINT] Closes #1079. Allow iterables for Line3DCollection
Merge pull request #2178 from mkcor/fix_commentout_mplrc

Commented line which was meant to be commented in the matplotlibrc.template
Fix for generating documentation

- Introduced a syntax error in PR #2161, whoops!
DOC - added the differences between the axes module namespace before and after
Merge pull request #2179 from tbekolay/doc_fix

Fix for generating documentation
Merge pull request #1931 from NelleV/axes_module

[SPRINT] Refactored the axes module to split it in smaller chunks.