more robust transitions to temporary modes

Dependencies

• [2] BYG5CEMV support for naming points
• [3] XNFTJHC4 split keyboard handling between Text and Drawing
• [*] BLWAYPKV extract a module

Change contents

• replacement in drawing.lua at line 482
  [3.10172]→[3.10172:10223](∅→∅)
  − Previous_drawing_mode = Current_drawing_mode
  [3.10172]

  [3.10223]
  + if Previous_drawing_mode == nil then

  + Previous_drawing_mode = Current_drawing_mode

  + end
• replacement in drawing.lua at line 492
  [3.10495]→[3.10495:10546](∅→∅)
  − Previous_drawing_mode = Current_drawing_mode
  [3.10495]

  [3.10546]
  + if Previous_drawing_mode == nil then

  + Previous_drawing_mode = Current_drawing_mode

  + end
• replacement in drawing.lua at line 502
  [2.1972]→[2.1972:2023](∅→∅)
  − Previous_drawing_mode = Current_drawing_mode
  [2.1972]

  [2.2023]
  + if Previous_drawing_mode == nil then

  + -- don't clobber

  + Previous_drawing_mode = Current_drawing_mode

  + end