fix a typo

Dependencies

• [2] EFMLTMZG bugfix: restrict strokes to the drawing they started in
• [3] OTIBCAUJ love2d scaffold
• [4] XX7G2FFJ intermingle freehand line drawings with text
• [5] KVHUFUFV reorg

Change contents

• replacement in main.lua at line 95
  [3.48]→[3.48:91](∅→∅)
  − propagate_to_button_handers(x,y, button)
  [3.48]

  [2.105]
  + propagate_to_button_handlers(x,y, button)
• replacement in button.lua at line 12
  [3.2443]→[3.2443:2494](∅→∅)
  − function propagate_to_button_handers(x, y, button)
  [3.2443]

  [3.2494]
  + function propagate_to_button_handlers(x, y, button)