Closes Homebrew/homebrew#66

We shouldn't mess with the user's PATH anyway. So assume our users are smart and just warn them about potential issues instead.

Our build directories are space-less, but the final destination may have
spaces, especially since OS X often uses your full name as your home directory
path.

That'll teach you!

Signed-Off-By: Max Howell <max@methylblue.com>

I added a unittest.

On Leopard you can enable it by defining the environment variable:

    HOMEBREW_USE_LLVM

I didn't enable it on Leopard by default because it doesn't get as much testing, and I don't want to rock the boat. On Snow Leopard people are forigiving of issues because it is new and many compiles fail anyway. And if you installed Snow Leopard you *want* the cutting edge.

Closes Homebrew/homebrew#29

Axel tries to accelerate downloads by using multiple connections (possibly to
multiple servers) for one download. Because of its size, it might be very
useful on bootdisks or other small systems as a wget replacement.

Signed-off-by: Max Howell <max@methylblue.com>

I adapted it slightly based on the user agent that Safari gives.

Closes Homebrew/homebrew#58

Closes Homebrew/homebrew#53

I'm trying to only show the interesting stuff. You can see a full listing with
brew -v list, or by piping to other commands.

Tell me if you hate it or love it.

Shows the git-log for that formula.

Random guy on Twitter mentions it. Google confirms.

Otherwise you run the risk of not running the exact version / make of the utility you planned.

Fixes Homebrew/homebrew#48

Really we need to do this formula too, so I guess a make and cmake function are on the way…

References issue Homebrew/homebrew#48

Stupidly I figured Ruby did this for us, but why would it?

Using the example from the existing code:

  CHECKSUM_TYPES.each do |type|
    if !instance_variable_defined?("@#{type}")
      class_value = self.class.send(type)
      instance_variable_set("@#{type}", class_value) if class_value
    end
  end

I extracted that block into a method 'set_instance_variable' which I
then used in all places where this behavior was being used.

You can now use "url", "version", "homepage", and any checksums as
class methods, like so:

    class Dos2unix <Formula
      url 'http://www.sfr-fresh.com/linux/misc/old/dos2unix-3.1.tar.gz'
      md5 '25ff56bab202de63ea6f6c211c416e96'
      homepage 'http://www.sfr-fresh.com/linux/misc/'
    end

The previous usage ("@url = 'http://example.com/tarball.tgz'") still
works, maintaining compatibility with previous formulas.

"dos2unix.rb" is translated into the new format as an example.

I used the same option flag as ruby gems does.

The code also makes sure to terminate with a newline, unless the
output is empty.

Using more Pathname methods.

Only show text if verbose mode is on, as is typical for the rest of our install output.

TODO: would be nice if we knew you were a dev and automatically enabled verbose mode perhaps.

Allow Formula.skip_clean? to prevent empty folders from being removed
as part of the brewing cleanup process.

Corrected README path.

Ohai is for titles, to separate sections of output so it is more readable, it
truncates long lines for this purpose. So don't use it if the line you are
outputting is likely to be long and important. Instead prefix that line with
a summary header.