matplotlib Code

A few more changes in examples

Fix negative contour linestyle specification in example

show proper way to change dash pattern of negative contours.

Repositioned second colorbar on fourth plot.

Make collections accept flexible mpl color specifications.

New version of colorbar, plus small bugfixes.

Fix setting of xtick.direction etc.

contour, contourf return ContourSet object; colorbar uses it

syncing to 0.73

fixed ticks on horiz cbar