refactor JACK MIDI port to allow writing from a non-process() thread, and move ARDOUR::MidiEvent into MIDI namespace along with midi_events.h header

git-svn-id: svn://localhost/ardour2/branches/3.0@3155 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/midi++2/SConscript

@@ -7,7 +7,13 @@ import glob
 Import('env libraries install_prefix')
 
 midi2 = env.Copy()
-midi2.Merge([ libraries['sigc2'], libraries['xml'], libraries['glibmm2'], libraries['glib2'], libraries['pbd'], libraries['jack'] ])
+midi2.Merge([ libraries['sigc2'], 
+	      libraries['xml'], 
+	      libraries['glibmm2'], 
+	      libraries['glib2'], 
+	      libraries['pbd'], 
+	      libraries['jack'] 
+	      ])
 
 if midi2['IS_OSX']:
 	midi2.Append (LINKFLAGS="-Xlinker -headerpad -Xlinker 2048")