Port audit_desc audit rules to a cop

audit: fix core formula alias check.

update-report: don't show new, installed formulae.

Was missing a formula object being passed.

These were those migrated from other taps but if they are installed
already: they aren't new to that user.

Revert "keg_relocate: Don't relocate dylib IDs containing metavariables."

Add Skylake to the Linux hardware list

java_requirement: Add newline to failure message

Signed-off-by: Bob W. Hogg <rwhogg@linux.com>

Xcode: update supported versions & download URLs for 8.3

Handle missing receipt on `brew install`.

For example if this is for a really old keg, keg where a user has
manually removed stuff or used `brew diy`.

ISSUE_TEMPLATE: tweak instructions.

Use `sudo` if parent path of `target` is not writable.

Be clearer about what's expected and where to file things.

Document all short flags.

Fix the 'export PATH' message in `link` for a keg-only formula

Commit 4cae6a72 introduced the message,
but it printed the wrong path, e.g. for `brew link sqlite`:

```
If you need to have this software first in your PATH instead consider running:
  echo 'export PATH="/usr/local/opt/sqlite:$PATH"' >> ~/.zshrc/bin
```

where `/bin` is appended at the end, but should be inserted before
`:$PATH`: `echo 'export PATH="/usr/local/opt/sqlite/bin:$PATH"' >> ~/.zshrc`.
This patch fixes that and updates a test to verify it.

keg: correctly remove alias symlinks.

Fixes #2427.

cask: remove pre_bug_report links

missing_formula: pillow lives in homebrew/science

Remove osmium from blacklisted formulas

Migrator: various rename fixes

Otherwise we could end up removing files unnecessarily.

This avoids needing to use `force: true` and still let's Homebrew do
what we want with our own taps.

ruby_requirement: fix path prepend