re-added lines to make sure that `bottom` and `left` are not None in
the case of `log=True`.  If this is not done, there will be type
exceptions.

Issue #1882
simplified logic related to bottom=None and log in `bar`
Added support for providing 1 or 2 extra colours to the contour routines to easily specify the under and over colors.
qt4_editor formlayout now works with colour tuples
Fixed call to path.Path.contains_point from pnpoly. contains_point accepts a list as its first argument.
@efiring's suggestion.
Deprecate the top-level functions in path.py
Remove deprecated code
Use new warn_deprecated helper function and decorator where appropriate.
Warn about incompleteness of CocoaAgg backend
Remove the Fltk backend
Remove the EMF backend
Add a what's new entry for the WebAgg backend
Request a specific version of Gtk when using gi
pep8 fixes
and fixed most of the long lines
questionable fix of overly long import lines
Remove FltkAgg from comment
Fix typo
Remove commented out stuff