Use active voice when applicable, better verbs & adjectives, preposition usage, proper tense, etc.

Another look at the current Rubocop rules and how they fit with our
existing and desired future style. Almost all of these changes were
automatic. Split some rules between formulae/brew where brew doesn't
have millions of cases that need fixed.

- Inconsistent or unneeded indentation
- Missing or superfluous empty lines
- Missing or wrongly formatted arguments in command summary
- Missing punctuation

Closes Homebrew/homebrew#47665.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Closes Homebrew/homebrew#42354.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

The heuristic for determining whether something is installed changes
from "f.installed?" to "f.rack.exist? and f.rack.subdirs.length > 0" in
order to properly consider outdated formulae.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

`brew doctor` shelled to `brew missing` and parsed the results.
When VERBOSE was true, this caused an error as extra, unexpected
output is generated.

Make missing an internal command, and give it a programmatic interface.