`jj cat` better matches `hg cat` and, of course, `cat`. I apparently
called it `jj print` when I added it in 7a013a59ae because I haven't
found `hg cat` useful for actually concatenating files. That's still
true, and I don't know if we will ever bother to teach `jj cat` to
actually concatenate files, but I think the familiarity of `cat` is
more important.
For reference, Git calls it `git show <rev>:<file>`.
I kept `print` as an alias and added a test for it. I also documented
the test better.
By the way, I've considered adding a command for writing from stdin
directly to a specific commit. If we ever do, it might make sense to
call that command `write` (e.g. `echo foo | jj write -r @-
README.md`). Then it would make sense to add `read` as an alias to
`cat`. I'm not sure that's a good idea, but let's leave that for later
anyway.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
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.
I'm adding this mostly because it's useful for testing. That's also
the reason it supports displaying conflicts. I didn't call it `cat`
like `hg cat` because I haven't found `hg cat` on multiple files
useful.
