beremiz

SVGHMI: detachable_elements.ysl2 becomes detachable_pages.ysl2, and includes logic to process pages elements. Other minor code moves.
<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"/>