Replaced ENV.gcc_4_2 + comments with calls to "fails_with_llvm",
to specifically message to the user when a formula is known or suspected
to not build with LLVM. If the user specifies "--use-llvm", the message
will be displayed, but compilation will be tried anyway.

Since using LLVM is now an advanced/hidden feature instead of the
default on 10.6, we'll let the user try anyway (and submit patches
if things are now working.)

Reinstalls out outdated brews.
See: http://github.com/mxcl/homebrew/issues/issue/1324

This external command allows you to switch between installed versions of
a formula. If you have multiple versions of a formula in your cellar, the
standard "brew link" command will refuse to run.

This new command "brew switch" tries to unlink all versions of the brew
from the prefix, then links the specific requested version.

External command "brew fetch" now allows -f|--force to remove an
existing cached file before downloading.

When an "install -d formula" fails, and the user gets dropped into an
interactive shell, set the HOMEBREW_DEBUG_INSTALL env var to the name
for the formula that failed. Also set variable if the user requests an
interactive install in the first place.

Note that this may be different than the formula being installed, since
it may have been a dep that failed.

Also remove todo in utils; users can now look for HOMEBREW_DEBUG_INSTALL
in their prompt command, and adjust their prompts accordingly.

Plus more reassuring preamble.

Includes: generator script, ronn source, manpage output

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

Man page updates.

* Generator command is now an external command with additional options
* Added more brew commands
* Tweaks and reformats

If the user has, for instance, a non-system "xml2-config" in the path
ahead of the system and Homebrew folders, ./configure scripts which
look for and use this config script will get confused.

This command looks for Cocoa Applications (.app bundles) in the prefix
of all installed formulae. If any are found, they are linked into
"~/Applications", the system-defined location for per-user apps.

A formula using svn can now provide a spec:
    :revisions => {...revision numbers...}
that contains a mapping of revision numbers to use
for externals.

The name of the external is keyed to the revision to
use for that external.

The symbol :trunk should be used to specify the reivsion
of the main repo.

An example from the Ffmpeg formula:
    head 'svn://svn.ffmpeg.org/ffmpeg/trunk

',
        :revisions => { :trunk => 22916, 'libswscale' => 31045 }

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

Now makes use of `svn up` to make cache act like
a cache. Externals without a revision specified
are now checked out at HEAD, whereas before they
were ignored. Escaping arguments to backticks.
Making sure main repo is checked out before the
externals.

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

See:

* http://github.com/mxcl/homebrew/issues/issue/1359
* http://github.com/mxcl/homebrew/issues/issue/1438

Homebrew will now look for external commands that are +x on PATH, named
as "brew-<cmd>" or "brew-<cmd>.rb"

* Shell scripts are exec'd with some HOMEBREW variables set in the ENV.
* Ruby scripts are require'd directly.

See: http://wiki.github.com/mxcl/homebrew/external-commands

* Move 'brew doctor' above both unknown command blocks and then...
* Merge unknown command blocks.

(This is cleanup for supporting external brew commands.)

This allows formulaes which use CVS to support:
  brew --cache [formula]

If a formula name is passed to "brew --cellar", output the location of that
brew in the Cellar (which will be "brew --prefix (formula)" without a version
sub-folder.)

This allows for:
  rm -rf `brew --cellar node`
for deleting all versions of node, installed or not.

Fixes Homebrew/homebrew#1514.

Like pkgconfig, perl5 & php, we don't want any one formula to "own" the
lib/python2.6 path.

Fixes Homebrew/homebrew#1218.

Homebrew expects manpages to be linked in shared/man/...
and not man/...

sceaga maintains Tiger and PPC support for Homebrew, so change our error
messages to refer to his branches.

* Add --config
* Alphabetize various lists
* Remove some local temp variables

Between the quick-install steps and other instructions on the Wiki,
this "self-link" script is no longer needed (and no longer recommended.)

Similiar to "brew create --macports", using --fink will do the corresponding
search for Fink packages.