some early returns should be asserts

Dependencies

• [2] DRFE3B3Z mouse buttons are integers, not strings
• [3] G6OYAYHU paste in text with M-v
• [4] VJ77YABH more efficient undo/redo
• [5] XNFTJHC4 split keyboard handling between Text and Drawing
• [6] 4QQBMWLL regression: typing uppercase letters in text
• [7] PFT5Y2ZY move
• [8] 2ZYV7D3W handle tab characters
• [9] BYG5CEMV support for naming points
• [10] JFFUF5AL override mouse state lookups in tests
• [*] BULPIBEG beginnings of a module for the text editor

Change contents

• replacement in text.lua at line 142
  [2.1182]→[3.1:74](∅→∅),[3.1248]→[3.1:74](∅→∅),[3.113]→[3.1:74](∅→∅)
  − if App.ctrl_down() or App.alt_down() or App.cmd_down() then return end
  [2.1182]

  [3.1174]
  + assert(not App.ctrl_down())

  + if App.alt_down() then return end

  + assert(not App.cmd_down())