Added functionality for plotting the actual violin bodies to violinplot.

Conflicts:
	lib/matplotlib/axes/_axes.py
violinplot: Renamed some input/output parameters more appropriately. Added some handling for arbitrary length input vectors

Conflicts:
	lib/matplotlib/axes/_axes.py
Added ksdensity (KDE) function in mlab and adapted _axes violinplot function to accept new KDE.

Conflicts:
	lib/matplotlib/axes/_axes.py
Added basic violinplot demo in examples
added disclaimer for ksdensity and changed return type to dict
Added lines to the violinplot function
Fixed mean/median for kde dict result
Added flags to violinplot which toggle whether various values of interest are displayed on the violin plots
violinplot: Added check for hold status, tidied up a bit
violinplot: Fixed up return values
Fixed pep8 compliance in ksdensity
Added horizontal violin plot feature compatible with means, extremas and medians.
Fixed bug for regression test #1181 in scipy unit tests; ksdensity is now referred to as gaussian_kde and exists as a class in mlab.  Updated violinplot examples with up-to-date customization options
Fixed list comp position bug and updated examples
Reverted 69b304c.
Fixed pep8 issues in violinplot
violinplot: Refactored a bit to reduce pylint warnings
Re-added points parameter to violinplot. Updated signature documentation
Merging for pep8 compliance for mlab's GaussianKDE
Added skeleton skeleton tests for violin plot