* added to_string(), to_xml() and from_xml() to MIDI::Event
* added partial support for midnam-Patchfiles (http://www.sonosphere.com/dtds/MIDINameDocument.dtd): midnam_patch.h/.cc
* added validation support to xml++.cc/.h
* added XMLNode::add_property(const char *name, const long value)
* added test to pbd/tests/xpath.cc
git-svn-id: svn://localhost/ardour2/branches/3.0@3412 d708f5d6-7413-0410-9779-e7cbd77b26cf
