fixed a bug in qt4's save_figure function
removed a lingering print statement
Added a Qt4Agg backend
fixed a usetex bug on windows
PDF bugfixes
PDF clip rectangles
draw_arc in PDF backend
Update docstrings for interp functon.
Missing paren in axes3d.py.
Quadmesh bugfix in backend_bases; prevent vmin==vmax in set_[xy]lim.