SVGHMI: added a widgets description object, accessed by id. Added frequency to widgets, as separate template to allow future customization. Excluded non svg elements (i.e inkscape Sets) with HMI: labels from widgets.

                  <xsd:element name="Linux">
                    <xsd:complexType>
                      %(toolchain_gcc)s
                    </xsd:complexType>
                  </xsd:element>