SVGHMI: Add "lang" permament persistent HMI_LOCAL variable to reflect selected language, apply stored language choice at startup and make it always subscribed to a pseudo widget (as for hearbeat) that apply language choice when it changes.
<xsd:attribute name="Compiler" type="xsd:string" use="optional" default="gcc"/>
<xsd:attribute name="CFLAGS" type="xsd:string" use="optional" default=""/>
<xsd:attribute name="Linker" type="xsd:string" use="optional" default="gcc"/>
<xsd:attribute name="LDFLAGS" type="xsd:string" use="optional" default=""/>