REL: v1.5.0

This release of matplotlib has several major new features:

 - Auto-redraw using the object-oriented API.
 - Most plotting functions now support labeled data API.
 - Color cycling has extended to all style properties.
 - Four new perceptually uniform color maps, including the soon-to-be
   default 'viridis'.
 - More included style sheets.
 - Many small plotting improvements.
 - Proposed new framework for managing the GUI toolbar and tools.