bugfix: handle drawings when updating screen top

Dependencies

• [2] TGHAJBES use line cache for drawings as well
• [*] BULPIBEG beginnings of a module for the text editor
• [*] ODLKHO7B switch to line index in a function

Change contents

• edit in text.lua at line 925
  [5.712]

  [2.1499]
  + if line.mode ~= 'text' then return end