Extensible select and enumeration types

and their elements in schema Text_representation_arm taking into account BASED_ON types


 font_select - EXTENSIBLE GENERIC_ENTITY SELECT
          Draughting_pre_defined_text_font
          Externally_defined_text_font
          Text_font

 identification_item - EXTENSIBLE SELECT

 measure_value - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          length_measure
          plane_angle_measure

 point_select - EXTENSIBLE GENERIC_ENTITY SELECT
          Cartesian_point
          Point_on_curve
          Point_on_surface

 text_alignment - EXTENSIBLE ENUMERATION
          bottom_centre
          bottom_left
          bottom_right
          centre_centre
          centre_left
          centre_right
          top_centre
          top_left
          top_right

 text_delineation - EXTENSIBLE ENUMERATION
          overline
          underline