renamed axesPatch, axesFrame and figurePatch to be less redundant
use plain text rather than text image for watermark example
added simple watermark examples
added origin support for composite images
Removing redundant cla() method. (Thanks Tony Yu).
fixed pixel border bug for composite images (eg layer_image.py)
Add a generic PatchCollection class.
added array and png helper funcs to mathtext
added date index formatter example
added api histogram demo which comments on the new bins return value
