matplotlib Code

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

removed reserved name "as" from some examples

updated backend driver to find the new fill_between examples

renamed fill_between.py and fill_betweenx.py to have _demo postfix

added example to fill_between to show how to create multiple axes spans where a condition is true

added example to fill_between to show how to create multiple axes spans where a condition is true

added JJ's F/C two scale example

axes_grid: initial checkin of curvelinear grid support

axes_grid: fix broken spine support

Add set_color() convenience method to Spine class