Add ability to diff branches.

[CDA0]

When comparing the modules changed an option to compare against the branch tags already created rather than comparing against main. This allows for reruns not to create tags.

Bug fixes:

• fix an issue where modules with the same word in them would pick the wrong tag.
• fix an issue where removing a file would not generate a tag. (fixes Vertag doesn't detect a change when a file is deleted in a module #4)