SVGHMI: split page switch into switching subscription and switching elements in the DOM, to ensure that subscriptions have been send before changing DOM, and avoid some flicker.
<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"/>