Add "verbose" config option, defaulting to true.

Only `puts` if "verbose" is set to true.
Actually, instead of `puts`, write to stderr.
Commentify Gekyll default settings.
Fix big bug in Tree.recurse.

Should have tested that earlier.
Add support for non-bare repos.
Change `default_layout` to `layout` in config.

This is a minorly-breaking change, but I don't get the sense that enough
people are using Gekyll yet -- let alone this specific config parameter
-- to make it a problem. Hopefully.
Move crude-repo-page.html to repo.html.

Had caused some confusion. Now, given the default layout parameter,
the sample repo should work "out of the box" without needed to be
renamed or requiring the author to tweak a post's YAML header.
Create `log` method.

DRYing out.
Tweak dest. path for certain Jekyll permalinks.

That is, for Jekyll permalinks that aren't directories, e.g.,

site.com/posts/my-post.html
 -- instead of  --
site.com/posts/my-post/

This ensures that Gekyll has a directory in which to write its extra
files, like commits.json, diffs/, and raw/.
Add version number.
Move TODO to its own file.
Add CHANGELOG.md.