cmd/sh: set working PS1 for zsh

The `bash`, default one is broken on `zsh`.

Fix issue where keychain github credentials wouldn't work

formula_desc_cop: ensure no full stops at the end of desc

- This was a suggestion by Mike McQuaid in my `homebrew-core` audit
  description PR. Based on ilovezfs's incantation `grep -r -E 'desc
  ".*\."' *.rb`, some formulae descriptions do end in full stops. (My
  initial assessment of this failed to account for the fact that
  descriptions are strings and so end in `"`.)
- Add an autocorrect for this cop, too.

bump-formula-pr: always use HOMEBREW_PATH.

system_config: get perl/ruby from HOMEBREW_PATH.

Fixes this when using environment filtering.

This is the actual user path when env filtering is enabled.

tap-info: handle APFS returning hash order

lock.sh: suppress error output when looking for flock

lines_cop: add missing e.g. clang++ regex SOL.

You need a start of line check in this regex (like was added in the
others) to allow things like `#{bin}/clang++`.

Fixes (on centos6):
which: no flock in (/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)

rubocop.yml: reduce tap maximum line length.

rubocop: disable length checks.

Unhide readall and update-reset from manpage.

java_requirement: support prompting users to install legacy Java casks

These are both tools that end-users can find useful on occasion so it
doesn't make sense to hide them.

We should keep these enabled for Homebrew/brew but for taps these just
end up being annoying and making `brew style` fail for little benefit

lines_cop: Fix detection of negated expression

This enhances the Java requirement to support prompting the user
to install the correct legacy Java version via Cask for formulae
that don't yet work with the latest version of Java. Previously,
even if the formula had a strict requirement that a specific,
older version of Java be used, the messaging would tell the user to
`brew cask install java` (i.e. to install the latest version of Java),
which wouldn't actually satisfy the requirement.

docs: fix poor visibility in syntax highlighting

rubocop-cask: 0.15.1

lines_cop: fix clang detection.

Rubocop 0.51

Fixes querying Cask commands' help