Copyright-holder and year information is extracted from git log.
git history begins in 2005. So (C) from 1998..2005 is lost. Also some
(C) assignment of commits where the committer didn't use --author.
Separate Snap from Grid. Lots of naming changes.
Multiple simultaneous snap options allowed. Grid is one of the possible Snap options.
Grid uses the same data as the rulers. Replace complicated tempo_lines with simple grid_lines.
The Grid is zoom-scale-sensitive along with the rulers. If you are zoomed out, grid becomes coarser.
