I feel the original -------/+++++++ pair is slightly confusing because
each half can be a separator by itself. I don't know what character other
than '-'/'+' is preferred, but let's pick '%' (for "mod") per @martinvonz
suggestion.
We used to have documention about how conflicts are implemented, but I
removed that a long time ago when I rewrote the README to target users
rather than VCS hackers. Let's have a doc for the VCS hackers (and
curious users) as well, though.
