Fixed the _absurd_ error that was preventing everything from working!.
Basically, I forgot to move a pointer forward (++) when a certain condition was met that didn't need treatment of the data.
Nevertheless the pointer had to be incremented!.

Now that was solved along with a possible division by zero pointed out by pippin.

This new alpha-aware convolution was tested with all common colorspaces as well as the painterly framework, I am aware that it breaks convolution for the painterly framework but it fixes it for all other colorspaces!.