* Carve out TITLE_BLOCK from BASE_SCREEN
  * Add include/hashtables.h and put class PROPERTIES in there.
    Change PROPERTIES to use "const char*" as the key instead of wxString.
++eeschema
  * Add shim class SCH_BASE_FRAME which introduces the data model SCH_SCREEN
    to the frame EESCHEMA frame class hierarchy and allows sharing of:
    SCH_SCREEN* GetScreen() const;                              // overload EDA_DRAW_FRAME
    void SetPageSettings( const PAGE_INFO& aPageSettings );     // overload EDA_DRAW_FRAME
    const PAGE_INFO& GetPageSettings () const;                  // overload EDA_DRAW_FRAME
    const wxSize GetPageSizeIU() const;                         // overload EDA_DRAW_FRAME
    const wxPoint& GetOriginAxisPosition() const;               // overload EDA_DRAW_FRAME
    void SetOriginAxisPosition( const wxPoint& aPosition );     // overload EDA_DRAW_FRAME
    const TITLE_BLOCK& GetTitleBlock() const;                   // overload EDA_DRAW_FRAME
    void SetTitleBlock( const TITLE_BLOCK& aTitleBlock );       // overload EDA_DRAW_FRAME