(make_lispy_position): New function for generating

(make_lispy_position): New function for generating
mouse click positions from frame and pixel coordinates.
Enhanced to return buffer position and actual row/column for
events outside the text area using updated mode_line_string and
marginal_area_string functions.
Return left-fringe and right-fringe clicks as such, rather than
clicks in text area.
(make_lispy_event) [USE_X_TOOLKIT, USE_GTK]: Don't call
pixel_to_glyph_coords, as we never use the results.
(make_lispy_event): Use make_lispy_position for MOUSE_CLICK_EVENT,
WHEEL_EVENT, and DRAG_N_DROP_EVENT to replace redundant code.
Eliminate unused code in WHEEL_EVENT handling.
(make_lispy_movement): Use make_lispy_position.