This is needed for the intersection code in `brew deps` to work right,
but can hopefully be refactored away somehow eventually.

Inheriting from Array (and other core types) is problematic:

  - It exposes a very wide interface with many methods that are not
    really relevant to the subclass.
  - It can cause some weird side effects, as many Array operations are
    in C and have hardcoded return values; for example, combining two
    array subclasses returns a new Array instead of the subclass.

Avoid these problems using delegation and the Enumerable module where
applicable.

Tests can now be specified as a block in the DSL. A temporary test
directory is set up automatically when calling Formula#test. The
semantics of the test remain the same: the block can either raise an
exception or return false to signal failure.

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

Closes Homebrew/homebrew#16280.

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

Closes Homebrew/homebrew#16901.

Superenv scripts have a stripped PATH, which may not include
the brew binary itself. Make this explicitly available to
superenv scripts.

Fixes bsdmake wrapper.

Closes Homebrew/homebrew#16805.
Closes Homebrew/homebrew#16846.

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

Fixes Homebrew/homebrew#16857.

Probably a better approach than reverted e721c7.

Fixes Homebrew/homebrew#16604.

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

Xcode.prefix and Xcode.installed? use slightly different heuristics to
find Xcode. In fact, .installed? basically duplicates a portion of the
.prefix logic. In practice, the methods results are usually consistent,
but .installed? does not handle non-standard prefixes if mdfind cannot
locate Xcode (for example, if the user has disabled Spotlight indexing).

Since .installed? is essentially a subset of the .prefix logic, we can
rely on the result from .prefix instead.

Fixes Homebrew/homebrew#16790.

@sceaga has discontinued his homebrew fork, so tigerbrew is now PPC/
Tiger users' best bet.

Originally written for tigerbrew, but useful enough for core.
Replaces the shelled-out which in utils.rb with a native-ruby
equivalent, which is moderately faster.

Closes Homebrew/homebrew#16659.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>

* Remove the unused HTML and commenting features.
* Return a good status code.
* Print command output on failure.
* Test bottle installation.

c.f. Homebrew/homebrew#16296.

c.f. Homebrew/homebrew#16688.