- Without this, `brew man` produces a lowercasing diff that violates
  Vale's rules.
- Also run `brew man` to test this out, and that updated some dates to
  December.

This variable allows a user to configure how often `brew update` runs.
With the previous implementation, however, it was still pretty slow as
it would run some of `brew update` even within the timeout. This feels
related to complaints about Homebrew "feeling slow" since we enabled
this. Address this by:

- making `HOMEBREW_AUTO_UPDATE_SECS` behave more like
  `HOMEBREW_NO_AUTO_UPDATE` and entirely skip the invocation of
  `brew update` if the relevant tap (homebrew-core or homebrew-cask
  depending on command invoked) has been checked in the last
  `HOMEBREW_AUTO_UPDATE_SECS`
- Only require/check the update of a single tap rather than every tap
- Increase the default value of `HOMEBREW_AUTO_UPDATE_SECS` from 1m
  to 5m to cut people a bit more slack. We're not updating things
  often enough for 1m not to feel a bit overkill and 5m feels
  appropriate for a Homebrew "session" to only require a single update.

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

Reorder switches as force/quiet/verbose/debug, --installed before --all, and link to SPECIFYING FORMULAE from top of page.

Fixes #6300

Today the Homebrew maintainers elected a new PLC, TSC and project lead.
Documentation is to follow detailing exactly the responsibilities for
each of these roles but adjust these to reflect the current state until
that point.

- Move `odeprecated` to `odisabled`
- Remove `odisabled`
- Enable automatic cleanup on install/reinstall/upgrade.

This change fixes a syntax error introduced in b278165d

If set, Homebrew will fail if on the failure of installation from a
bottle rather than falling back to building from source.

- Add some `odeprecated`
- Make some `odeprecated` now `odisabled`
- Remove `odisabled` code.
- Remove old update migrations
- Remove GCC 4.0 compiler
- Remove Tiger-only code
- Remove 32-bit-only code
- Remove use of LD64
- Remove GCC 4.3 - 4.8 support.

This will become the default in a later version of Homebrew but has an
opt-out through HOMEBREW_NO_INSTALL_CLEANUP.

Also, always cleanup files older than 120 days and set the general
default value for "old" logs, casks etc. to 30 days.

more.

     `brew`'s `man` page's 'ENVIRONMENT' section is intended to list only those
environment variables that users can set, not any that Homebrew sets as part of
its operation.

Note that the `HOMEBREW_FORCE_BREWED_` vars are automatically set if the system `git` and `curl` are too old. Drop mention of `HOMEBREW_GIT` which isn't user-settable.

Replace <var> tags with markup for italicized monospaced text in Markdown.
This requires the source to not combine bracketed and backticked text.

Work around ronn's inability to nest indents within list items by modifying its output to add a line break and indent after lines ending with a colon that aren't a list item's first line. This allows `brew.1.md.erb` to join the commands' help text without extra line breaks, which avoids the issue where kramdown was turning any command specs containing pipe characters into tables in the HTML output.

And remove the Homebrew/homebrew-core lead maintainer role.

Also add some who were missing (sorry folks) and our Linux maintainers.

Let's document these so people know who the leadership team behind the
project is.

Rather than relying on a `HOMEBREW_FORCE_BOTTLE` variable (which ends
up doing silly things like forcing bottle usage even when options are
provided) instead handle this at the `or_later` bottle detection
level so on prerelease versions of macOS any bottle looks like an
`or_later` bottle (unless various environment variables are set).

Fixes issues noted in:
https://github.com/Homebrew/brew/pull/4520#issuecomment-407229605

This does the equivalent of always passing `--force-bottle`. This will
be enabled by default on Mojave to allow people to avoid building
everything from source until our porting and bottling is a bit further
along.

* update references in `--cc` flag, using modern gcc examples
* note that issues should not be filed if `--cc` flag is used
* remove reference to `HOMEBREW_CC` as it should not be exposed to users
* generate manpages using `brew man` with these changes

Properly update man pages using the local brew executable (from the repo),
and copy the man pages to the repo.

Because of this messing with the user's path:
https://github.com/Homebrew/brew/blob/
    efc02899/bin/brew#L68
brew uses /usr/bin/git over brewed git, even when the former is
problematically old.
There may also be other reasons a user prefers to use brewed git.

There was already a HOMEBREW_FORCE_BREWED_CURL option and a
HOMEBREW_SYSTEM_CURL_TOO_OLD check to set it. This mostly copies those
to implement HOMEBREW_FORCE_BREWED_GIT & HOMEBREW_SYSTEM_GIT_TOO_OLD.

See also: https://github.com/Linuxbrew/brew/issues/736