This allows changed formulae in taps to be tested in the proper order.
See #738 for more details.

Add --full-name option to brew deps command,
which displays the full name of dependencies.

formulary: handle @ formulae.

Before this change:
```
~> brew search openssl@1.1
openssl@1.1 
==> Did you mean to perform a regular expression search?
==> Surround your query with /slashes/ to search by regex.
```

brew: execute update before tap

This seems generally like a good idea given that we're making syntax changes to
formulae & are going to keep doing so for a little while yet. Taps may have moved
over to that syntax, which then causes tap failures if brew isn't up-to-date.

Should fix situations like https://github.com/Homebrew/homebrew-php/issues/3545.

Don’t use `should` syntax in rspec.

* Replaced ; with && under Update Bug in README.md.

* Updated issue template's brew update fix.

Brew-Test-Bot-For-Core-Contributors: fix broken link

Fix missing `magenta` in Tty.

Remove `exist?` check for `brew-cask-tests.rb`.

cask tty removed

Restrict TMPDIR etc. changes to install, post_install and test

See discussion in Homebrew/brew#800.

various: update CI links.

brew.sh: complain when running Homebrew as root.

As discussed: announce that we are deprecating running Homebrew as the
root user as it's insecure and requires disabling the sandbox.

Fixes #796.

diagnostic: tweak /usr/local messaging.

Highlight that the main reason for preferring /usr/local is because of
bottles. There's been some confusion around this e.g.
https://github.com/Homebrew/homebrew-core/issues/3968

config: set TMPDIR, TEMP and TMP to HOMEBREW_TEMP

Improve HOMEBREW_BREW_FILE unset failure case.

Unify heredoc style.

Allow per-cask `cleanup`.

Print a better exception message and handle this in more cases rather
than producing confusing errors when it’s unset.

bin/brew: improve $HOMEBREW_REPOSITORY/bin/brew handling.

brew.sh: don't require /usr/local/Cellar creation.