Add copyright_diff() to DeltaCode object

[johnmhoran]

• Partial implementation of Add support for copyright holder diff #43.
• Continuation of Add Copyright class #82.

Work will include:

• Figure out initial copyright scoring, e.g.,
  • copyright change = modified + 5
  • copyright info removed = modified + 10
  • copyright info added = modified + 15
• Create corresponding copyright tests
  • Copyright only -- no license role
  • Combined copyright and license testing
  • But no need for tests re below cutoff score, since no longer used.

[johnmhoran]

@MaJuRG I've modified a number of existing tests, and created new tests, in issues #82 and #83 (commits already pushed). I have several more in mind and will add them and then move on to the next issue(s). (Thinking of tackling #84 next, then perhaps #71, #79, #81, #75, #72.)

When you have the chance, I'd welcome your thoughts on 82 and 83 including any additional tests.

Please note that my branch for 82 was created from develop and the branch for 83 was created from the 82 branch -- so my next branch(es) will be created from 83 until we've merged 82 and 83. Per our protocol, let me know when I can open a PR for 83 (which would, I think, encompass 82 as well) and I'll do so.

[steven-esser]

@johnmhoran Ok why dont you open a PR for all the stuff youve done for #82 and #83 since that will be easier for me to diff.

[johnmhoran]

Will do @MaJuRG . I've identified a number of additional new tests related to adding the Copyright class and copyright_diff(), but am working on them -- not yet added. Likely will be done by the end of the day. Shall I go ahead and open the PR, or wait till I've finished, committed and pushed those tests?

[steven-esser]

You can go ahead and add the tests in the open the PR.

[johnmhoran]

Open the PR now and then add the additional tests when done, or add the tests and then open the PR?