(make_lispy_position): Use modified mode_line_string,

(make_lispy_position): Use modified mode_line_string,
buffer_posn_from_coords, and marginal_area_string functions to
include both string object and image object in the lispy position.
Also add actual glyph width and height to position.
(read_key_sequence): Use real buffer position from mouse
event to find keymap property even when click is in marginal area.