Add --on-plc-start --on-plc-stop and --status-change to runtime command line, calling given command respectively on start stop or any event. Command line string is python formated (to eventually include status with {}) before being split (supports quoted strings) and passed to Popen for non-blocking execution.

          <xsd:attribute name="Command" type="xsd:string" use="optional" default="make -C %(buildpath)s all BEREMIZSRC=%(src)s BEREMIZCFLAGS=%(cflags)s MD5=%(md5)s USE_BEREMIZ=1 FROM_BEREMIZ=1"/>