DOC: documents coordinate conventions for 2D DWT routines.  Closes gh-213.
DOC: documents coordinate conventions for 2D DWT routines.  Closes gh-213.

rgommers/pywt,eriol/pywt,rgommers/pywt,grlee77/pywt,rgommers/pywt,michelp/pywt,rgommers/pywt,eriol/pywt,grlee77/pywt,michelp/pywt,michelp/pywt,PyWavelets/pywt,PyWavelets/pywt,eriol/pywt