add annotation_demo3.py
refactor Annotation to support arbitrary transformation.
update transform_scalar and transform_vector docstrings.
fix typo in previous commit
added order=3 option to interp
cntr.c: declare variables at start of block; fixes 2933705
cntr.c: patch by Ian Thomas to fix bug ID 2956378
Add pyplot.fig_subplot, for easier creation of figures with multiple subplots.
add Ben Axelrod's button patch for RectangleSelector
support LogNorm as arg to hexbin
