add __enter__ and __exit__ to PdfPages
multipage pdf: show usage of with statement in example
docstring fix
Merge pull request #2421 from megies/patch-2

Docstring fix
Remove dead RMS computation code
Merge pull request #2426 from mdboom/testing/remove-dead-rms-computation

Remove dead rms computation
Merge pull request #2319 from tacaswell/draw_idle_fix

fix draw_idle reference in  NavigationToolbar2
Add webagg api docs
Document API change in hist
only show preferred usage of PdfPages in examples
show only preferred usage for PdfPages and use preferred pyplot import
style
Merge pull request #2271 from mdboom/add-webagg-docs

docs: add webagg-backend
Merge pull request #2416 from megies/multipage_pdf_with_statement

Multipage pdf with statement
Merge pull request #2430 from neggert/hist_doc

Document API change in hist
Added check in autoscale_None for completely masked pcolor plots.
Explict exceptions when setting locale.
Updated coding standards test to raise an exception containing the PEP8 failiures.
Merge pull request #2436 from mdboom/locale-explicit-exception

Catch explicit exceptions when setting locale.
Clear the font caches on every test.  This should prevent problems where setting font properties will leak over into another test.
Fixed failing PEP8 tests.