Deprecate brew (un)linkapps.

xcode, xquartz: use default location when possible.

formula: return runtime_dependencies in to_hash.

formulary: read from formula in opt prefix.

Xcode can be installed anywhere but for most people it's in
`/Applications/Xcode.app` so just look there if `xcode-select` isn't
helpful before looking at Spotlight which can return weird results on
e.g. backup disks.

Fixes #1587.

Xcode can be installed anywhere but for most people it's in
`/Applications/Xcode.app` so just look there by default before looking
at Spotlight which can return weird results on e.g. backup disks.

We want to prefer the newer/versioned formulae when possible but this
is preferable to a random cached formula or, worse, no formula.

This means `brew info foo` will never complain that `foo` is a missing
formula.

Which, in turn, provides it for `brew info --json=v1` so other tools
such as e.g. `brew bundle` can make use of this information.

Unfortunately `brew linkapps` cannot behave nicely with e.g. Spotlight
using either aliases or symlinks and Homebrew formulae do not build
"proper" `.app` bundles that can be relocated. Instead, please consider
using `brew cask` and migrate formulae using `.app`s to casks.

audit: check virtualenv and setuptools resource.

bump-formula-pr: check for URL presence.

`virtualenv_install_with_resources` will automatically define and
install a `setuptools` resource so this is unnecessary.

References https://github.com/Homebrew/homebrew-core/pull/8570

If it's not there, produce a nicer error.

Fixes #1805.

keg_relocate: Check HOMEBREW_TEMP's realpath when excluding name changes

Since /tmp (the default HOMEBREW_TEMP) is a symlink to /private/tmp,
some build systems (like Parrot's) will attempt to use the realpath
instead of the literal /tmp we supply it with. This breaks the relocation
code, which only tested the literal HOMEBREW_TEMP and not its realpath.

Allow `brew audit` to fake a Safari user-agent.

This allows us to detect if homepages such as e.g. `aiccu` which
blocks `curl` are up or not.

Revert "uses: properly handle untapped formulae in recursive dependency expansion"

uses: properly handle untapped formulae in recursive dependency expansion

PerlRequirement: Perl version string may lack parentheses

Whitelist PHP formulas in shadowed header audit check

Revert "cc: always filter flags on deps."

keg: use resolved_path not realpath.

This guards against this being a non-symlink in which case it will fail.

Fix abv and prefix_linked?

Use docs.brew.sh links.

formula: correct grammar in comments

docs: fix titles on docs.brew.sh

licenses: update copyright year

For example:
This is perl, v5.10.1 (*) built for x86_64-linux-thread-multi