MAINT: Rename indices/counters in upsampling_convolution_full
MAINT: Rename indices/counters in upsampling_convolution_full

All array access in upsampling_convolution_full is now by use of indices,
rather than incrementing pointers. This makes clearer the required size of the
array.

michelp/pywt,rgommers/pywt,eriol/pywt,kwohlfahrt/pywt,michelp/pywt,PyWavelets/pywt,ThomasA/pywt,kwohlfahrt/pywt,eriol/pywt,aaren/pywt,rgommers/pywt,ThomasA/pywt,rgommers/pywt,grlee77/pywt,ThomasA/pywt,eriol/pywt,aaren/pywt,grlee77/pywt,michelp/pywt,PyWavelets/pywt,aaren/pywt,rgommers/pywt,kwohlfahrt/pywt