bugfix: imprecision in drawing

Dependencies

• [2] R3XGABER chunk up some long lines
• [3] VSBSWTE4 bugfix: where cursor is drawn
• [*] BLWAYPKV extract a module
• [*] NYQ7HD4D move
• [*] BJ5X5O4A let's prevent the text cursor from ever getting on a drawing
• [*] 5XQ4Y7NU reorg manual tests doc

Change contents

• edit in drawing.lua at line 129
  [2.1047]

  [6.1793]
  + -- recreate pixels from coords to precisely mimic how the drawing will look

  + -- after mouse_released

  + pmx,pmy = px(mx), py(my)
• edit in Manual_tests.md at line 15
  [3.1687]

  [8.168]
  + - analogously, how a shape precisely looks as you draw it