Redact igraph

This is already available in homebrew/science
open-babel: 2.3.2 patch to fix pybel's Molecule.draw + fix for Cairo

Added a patch that fixes Molecule.draw() in pybel.py (similar to upstream commit df59c4a630cf753723d1318c40479d48b7507e1c)
Also fixed the inclusion of the Cairo library and includes. Earlier the CMake directives were poiting to locations within the
open-babel installation. There also seemed to be a confusion between strings and arguments, giving cmake problems to understand
the directive.

Closes #20800.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
mpd: 0.17.4 and massive cleanup.

Add sqlite3 and libsamplerate as depends; they're small, and there's
really no reason not to want them.  Remove an unnecessary dep on mad
(ffmpeg can do everything it can).

Add :optional support for WavPack, JACK, and two-lame.

Make the deps for streaming output (libshout, lame, flac) optional.

Rename "--enable-soundcloud" to "--with-yajl" which, while less
informative, correctly controls the dependency on yajl.

Rename "--libwrap" to "--with-libwrap". Change its description to
reflect how it behaves differently on OSX <10.7, 10.7; remove on 10.8,
where it's useless.

Rename "--lastfm" to "--enable-lastfm" to follow the
options-start-with-verb conveition.

Document all of the options changes/quirks in caveats.

mpd moved from http://mpd.wikia.com/ to http://www.musicpd.org/ in April
2013.

Closes #19368.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
audit: don't try to audit missing deps

Refs #20829.
brew-test-bot: always write something to email file.
Don't use 'obj == nil'