Support of MusicXML 4.0

ProxyMusic version 4.0.1

• Support of MusicXML 4.0
• Support of Java 17
• Use of jaxb2-maven-plugin version 2.4
• Libraries uploaded to Maven Central

On the road to Audiveris V5

This is a minor release addressing the following goals:

• source code migration from Kenai to Github including the transition from Mercurial to Git and changing the package prefix from com.audiveris to org.audiveris
• a better integration with the upcoming version of the Audiveris software