spines and ticks: implement smart bounds
spines: attempt to fix initial placement bug
spines: be clear about meaning of location vertices
spines: default transform is in data units, add set_bounds() call
spines: simplify code
mplot3d: fix axes juggle issue, fix ticks on end of axes range
Don't limit notch size in boxplot to q1-q3 range
bugfix: mlab.prctile handles even-length data
tests: add unit test for prctile
draw_image api to use an arbitrary affine transform
