* code_map/model2.ml: better uses_or_users_of_node
* code_map/draw_microlevel.ml: capture out of bounds
* code_map/model2.ml: skeleton for lines_where_used
* code_map/model2.ml: lines_where_used first version
* code_map/model2.ml: fix bug line number
fix line issue, bottom_pos, rectangle above,
line starts at 0 or 1, many confusion
* code_map/draw_microlevel.ml: skeleton for magnifyer
* code_map/view_overlays.ml: first version magnifyer of uses and under cursor
* code_map/view_overlays.ml: do not magnify if does not need to