matplotlib Code

mplot3d: really add docs

add video lecture link to nav bar

Pixel-align even long sequences of rectilinear lines.

Improve alignment of markers.

special case 0,0 for atan2

mplot3d: update axes code, add support for '3D' text.
Split and add examples and begin documentation.

fix axes_grid/demo_parasite_axes.py

modifications to examples/docs to get them to build for the website

removed reserved name "as" from some examples

update doc strings to point to new fill between demos