How should we best credit copyright and contribution?

1. List copyrights by contributor and year in the source manually (our haphazard method now)
2. Blanket copyright to BVLC / BVLC + contributors at the top of the source and let the details be kept by versioning.
3. Generate a copyright list from git blame.

1 is dissatisfying since it requires effort to keep up-to-date both when new contributions are added and old contributions are replaced.

2 is simple, but does not give explicit credit in the source. However, the exact contributions of all authors are maintained in the versioning history and revealed by git blame and git log.

3 requires writing a script and bothering to run it or setting it up as a commit hook.