Fix cursor position overrun

[tompng]

When input lines is larget than screen height, and move cursor up and down, cursor position sometimes overruns
And if you input something, irb will crash. this pull request fixes it.
I think #470 will be fixed.

Left: before, Right: after
https://user-images.githubusercontent.com/1780201/224025150-fd53acd6-7ea1-42fc-8150-76001990518f.mp4

changes

calculate_nearest_cursor
...
update_previous_line_index
if @rerender_all
  update_line
  # forgot update_cursor_to_nearest_cursor_position
  rerender_all_lines
else
  update_line
  maybe_prepareing_instance_variables_for_moving_cursor
  update_cursor_to_nearest_cursor_position
  move_cursor
end

↓

calculate_nearest_cursor
update_cursor_to_nearest_cursor_position
...
# updating @line, @line_index, @previous_line_index are updated at once, used together in many place in line_editor.rb
update_line_and_previous_line_index

# rendering part
if @rerender_all
  # only doing rendering here
  rerender_all_lines
else
  # only doing cursor moving(≒ cursor rendering) here
  maybe_prepareing_instance_variables_for_moving_cursor
  move_cursor
end

[ima1zumi]

👍