start remembering where the cursor is drawn in px

We'll start using this in cursor up/down motions.

main.lua

@@ -44,6 +44,8 @@ Cursor_pos = 1  -- in Unicode codepoints, from 1 to utf8.len(line) + 1
 
 Screen_width, Screen_height, Screen_flags = 0, 0, nil
 
+Cursor_x, Cursor_y = 0, 0  -- in pixels
+
 Current_drawing_mode = 'line'
 Previous_drawing_mode = nil
 

text.lua

@@ -52,6 +52,8 @@ function Text.draw_cursor(x, y)
   love.graphics.setColor(1,0,0)
   love.graphics.circle('fill', x,y+math.floor(15*Zoom), 2)
   love.graphics.setColor(0,0,0)
+  Cursor_x = x
+  Cursor_y = y+math.floor(15*Zoom)
 end
 
 function Text.compute_fragments(line, line_width)