Java.txt: remove trailing whitespace
Java.txt: add comment about PixelsType search

This block of code, which specifically locates the PixelsType
corresponding to that of the source image, is lengthy enough to
warrant a descriptive comment and whitespace separation.
Java.txt: fix indentation levels
Java.txt: add comment for image creation step
Java.txt: standardize comment style
Java.txt: standardize descriptive header