Haiku Book: Midi2 fixes.

* Automatic whitespace cleanup.
 * Removed all of Midi2 from the "libbe" group, as they aren't part of it
 * Get rid of the redundant "libmidi2" group, as all of midi2 is already in
   the "MIDI 2 Kit" group, and the docs explicitly state that the MIDI 2 Kit
   has its own library.

docs/user/book.dox

@@ -469,9 +469,6 @@ snooze_until(time - Latency(), B_SYSTEM_TIMEBASE);
 		- <A HREF="http://www.io.com/~jimm/midi_ref.html">Jim Menard's MIDI Reference</A>
 
 
-	\defgroup libmidi2 (libmidi2.so)
-
-
 	\defgroup network Network Kit
 	\brief Classes that deal with all network connections and communications.