matplotlib Code

Slight documentation changes.

Changes to documentation of norm and orth functions and deprecation
warning for norm in favor of numpy version.

Update barb_demo.py to exercise more of the possible parameters for wind barb plots. Replace some confusing code for passing in the data with more explicit arrays. Also, make the data array for the arbitrary grid non-square so that proper dimensioning can be seen. Remove mysterious windows-styles line endings.

restored broken barb demo

restored interactive_bk var to backends init -- ipython shell uses it

Fix to is_scalar plus additional functions in cbook.py:

less_simple_linear_interpolation
isvector
vector_lengths
distances_along_curve
path_length
is_closed_polygon

converted barb demo to unix new lines

fixed is_scalar -- good catch david

added barbs method

add barbs method, barbs example.