- Remove taps that are (or will shortly be) deprecated.
- Remove commands that are only relevant to the boneyard (which will
  shortly be removed).

docs: code example reformatting

Add labeled fences to most code blocks, monospace terms where
appropriate, omit "$" when referring to variables

Also works around bug in Jekyll where a URL with a "#" will cause links
in the same paragraph to not have their extensions replaced by using
"#" instead.

pull: warn (not die) on bottle publish failure.

formula_installer: tweak req formula additions.

Rather than just checking if a requirement's dependency is installed or
not check if the requirement was actually satisfied by a particular
formula rather than e.g. just having a `default_formula` defined.

New-Maintainer-Checklist: be more explicit.

README: add some more shields.

migrator: allow new cellar to exist already

gpg: add GnuPG series 2.1.x to supported versions

Lets us migrate a formula to a name that may have previously been used.

If gnupg 1.x is installed as "gnupg" and gnupg 2.x is installed as
"gnupg2," it's currently not possible to rename gnupg2 -> gnupg, since
the 1.4 keg will already be installed in the "gnupg" Cellar, so in order
to reclaim the name "gnupg" to be used for 2.1, either 1.x must be
manually uninstalled, or the new cellar needs to be allowed to exist
already.

link: tell users of `brew link --force` about opt.

This is useful when you're pulling PRs where individual bottles can't be
uploaded/built but you still want to pull the PR as a whole anyway.

missing_formula: warn when git-log takes very long

For the current release, Travis CI and Coveralls status.

If people are force-linking keg-only things they should probably be told
that they can add the opt prefix to their PATH instead.

man: generate Markdown man page.

cd tap-new: fix symlink creation.

The existing `brew.1.html` wasn't particularly pleasant to read and
given everything else in `docs/` is a Markdown file it makes sense to
generate a post-processed Markdown file that can in turn be used by
Jekyll to generate a nicely themed HTML file.

Note some additional ways to help, gotchas and how to get started.

Ensure the full HOMEBREW_TAP_DIR path is created before deleting and
creating the symlink for it. This ensures that non-`homebrew` taps will
have the necessary username/organisation folder created.

Fixes #2378.

update-report: check migration symlinks.

Check if `HOMEBREW_CELLAR/old_name` is a symlink. If so, it's already
been migrated so can be skipped.

tests: unset HOMEBREW_TEMP

Hint at new location of migrated formulae

Setting `HOMEBREW_TEMP` env. var [currently] breaks tests (`brew
tests`). Although this behavior looks like a bug, the solution is
straightforward: unset `HOMEBREW_TEMP`.

formula_installer: need up to date requirement formulae.

audit: check system dupe deps on new formulae.

audit: deprecate depends_on :tex.

update-report: migrate all formulae every time.

update-report: migrated formulae were not deleted.

These methods belong together so combine them in a single class to
provide a simpler API.

This will allow extending this class so it can be used by more than
just blacklisting.