fix typo in figlegend_demo.py

otherwise y4 never gets used
Fix #3298.  Wedge's shouldn't special case the "round the horn"
Update demo_floating_axes.py
Update demo_floating_axes.py
Fix scaling of custom markers

See also #3441.
Count the uses of paths in a collection

Add a way for backends to query how many times each
path in a collection can be reused.
Use the uses_per_path data in pdf backend

Fixes matplotlib/matplotlib#3345
Add the new test in the list of tests
Add new baseline images for two tests

These look closer to their png counterparts than the old ones.
There probably is a remaining bug in the drawing of edges.
Handle path collections without stroke in PDF backend
Merge pull request #3 from mdboom/pdf-xobject-linewidth

Pdf xobject linewidth
Reduce the emitting of object definitions in ps and svg

The cost calculations are very rough, back-of-the-envelope.
In the example from #3345 I get significant file size reductions:

	2.3M	before.svg
	1.8M	after.svg
	916K	before.ps
	672K	after.ps
Adds multiple histograms side-by-side example
MNT : make sure to cast to unicode
BUG : make rcParams.update validates inputs

Close #3470

Over-ride `update` so that inputs are validated.
MNT : simplify and relax validation on nseq

Simplify and relax the validation for sequences of floats and
ints.

 - unified logic
 - input is not restricted to coma-separated lists, list, and tuples.
   any length 2 sequence (like an array) will now work.
BUG : validate_stringlist should drop empty strings

This is a minor api change, but I can't think of why one
would want to carry around empty strings.
BUG : give animation args valid default values
TST : minor tweaks to animation smoketests
TST : added tests for some validation functions