* Now link with XML support within wxWidgets.
  * Start of export the generic netlist in XML.  Still need to rework the chain
    loaded netlist plugin.
  * OBJ_CMP_TO_LIST class now uses a std::string to hold the 8 bit string m_Ref,
    but hides this behind accessors which provide for both Unicode and 8 bit
    set and get functions.
  * build_BOM.cpp retains the selected filename on subsequent runs as a default.
  * Code cleaning, especially in build_BOM.cpp.