Create interpolation_methods.py
Rename examples/api/interpolation_methods.py to examples/images_contours_and_fields/interpolation_methods.py
Update interpolation_methods.py
Fix dpi detection in tight_bbox (fixes #2586).
backend_pgf: use the bounding box as clip rectangle (fixes #2586)
Update interpolation_methods.py

Update according Phils suggestion.
Update interpolation_methods.py
Make standardization of input optional in mlab.PCA

In principal component analysis, standardization of input data should be a user choice, depending on the problem at hand. The current version always standardizes, without offering a choice to the user. Therefore, I added an option to the PCA class where the user can specify whether the input data are to be standardized before performing the PCA. When *standardize* is set to False, only centering is performed, without dividing by sigma. The default is to standardize, to remain compatible with the current version.
Merge pull request #2752 from aszilagyi/patch-1

Make standardization of input optional in mlab.PCA
Merge pull request #2621 from pwuertz/fix_2586

Simplify and fix dpi handling in tight_bbox
Merge pull request #2599 from RutgerK/master

Create interpolation_methods.py
first steps to extract FigureManager* and friends from pyplot

This commit refactors backend_bases into two parts, the Gcf
independent parts, which moved to backends/_backend_bases.py, and the
Gcf dependent stuff which stayed in backend_bases.py.  The contents of
backends/_backend_bases.py are bulk imported into backend_bases so
this change should be backwards compatible.

Added an attribute to FigureManagerBase for the _key_press_handler
function.  This might be a stop-gap if the logic in `Gcf.destroy` should
be moved into the FigureManager or canvas classes.
split backend_qt4 into two parts, with and without Gcf

added a static method to FigureManagerQt to gracefully patch in
the Gcf.destroy call back.  As with the _key_press_handler call back
this may be a stop-gap if that logic gets re-factored.
split backend_qt4agg into two parts.

One part (_backend_qt4Agg.py) has no dependencies on Gcf or pyplot,
which are all collected in backend_qt4agg.py.

Should be fully back-wards compatible.
Added a demo-file to show how to use the FigureManager classes to
get pop-up graph windows as part of a larger gui application.
removed un-needed import of Gcf
pep8 on backend_gtk.py

Two line-length violations on long urls in comments are left.
pep8 clean up in backend_gdk
removed un-needed Gcf import

changed imports to _backend_bases to avoid implicit Gcf import
split backend_gcf into two parts,
one which includes Gcf and one that does not.