Debugging the bit masking / setting issue
Partial fix in merge_plaintext_into_img_data
The masking was wrong before, and so was the indexing. It's partially fixed now, but the indexing is much slower now vs. using an iterator. need to figure out a way to get back to an iterator, but for now just need to get it working and will revisit performance tuning once it is functional. With a basic framework in place it is able to read in a text file, encode it (partially) into an image, and then write out the image.