Fixes Homebrew/homebrew#17010.

Closes Homebrew/homebrew#18041.

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

Array#count was apparently introduced in 1.8.7.

Fixes Homebrew/homebrew#18918.

Build 211 can build most things, but I've seen intermittent
miscompilation and slower code. Also it comes from Xcode 4.2, so most
people don't have it anyway. Let's use 218 as the minimum viable
version.

Closes Homebrew/homebrew#18886.

This was meant to support:

  env do |req|
    append_path 'PATH', req.some_method
    ...
  end

i.e., the block was evaluated in the context of ENV. But it turned out
to be not so useful after all, so I'm ripping it out before something
actually depends on it.

Sometimes we may want to run commands after bottle installation (such as
creating directories outside the Cellar) so this method allows us to do
so.

Closes Homebrew/homebrew#18382.

We want to notify users that non-/usr/local installs may result in some
bottles being not used.

References Homebrew/homebrew#18540

Don't complain if it's instantiating the class so that it can pass
arguments.

Fixes Homebrew/homebrew#18883.

Fixes Homebrew/homebrew#18885.

Grrr...

This may result in some undesired output for things that suppress
stdout, but we'll fix those as we go.

Fixes Homebrew/homebrew#18650.

Since `pinned?` was using `File#exists?`, broken symlinks left by force-upgraded
formulae made `pinned?` return false while `pin` returned with an error because
it could not overwrite the broken link. This is fixed by using `File#symlink?`
instead, which returns true for broken symlinks and false only when they do not
exist.

Closes Homebrew/homebrew#18858.

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

Closes Homebrew/homebrew#18851.

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

Closes Homebrew/homebrew#18849.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

* Added `pin` et. al. to manpage.
* Added `brew pin` to `brew.1` * Added `brew unpin` to `brew.1`
* Added `brew list --pinned` to `brew.1`
* Added information about frozen formulae to `brew upgrade` in `brew.1`
* Added `pin` et.al. to completion scripts.
* Unpin formulae when uninstalling them
* Unpin and re-pin formulae when upgrading (avoids stale symlink)

References Homebrew/homebrew#18386.
Closes Homebrew/homebrew#18515.

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