bugfix: backspace from start of final line

Dependencies

• [2] JJDT2X4F unnecessary args
• [3] UHB4GARJ left/right margin -> left/right coordinates
• [4] LF7BWEG4 group all editor globals
• [5] HMODUNJE scroll on backspace
• [6] SPSW74Y5 add state arg to Text.keychord_pressed
• [7] 2RXZ3PGO beginning of a new approach to scroll+wrap
• [8] XNFTJHC4 split keyboard handling between Text and Drawing
• [9] QCPXQ2E3 add state arg to a few functions
• [10] AYE2VEGJ extract a couple of methods
• [*] LXTTOB33 extract a couple of files
• [*] DSLD74DK lots more tests
• [*] BULPIBEG beginnings of a module for the text editor

Change contents

• edit in text_tests.lua at line 43
  [3.2318]

  [13.1482]
  + end

  +

  + function test_backspace_from_start_of_final_line()

  + io.write('\ntest_backspace_from_start_of_final_line')

  + -- display final line of text with cursor at start of it

  + App.screen.init{width=120, height=60}

  + Editor_state = edit.initialize_test_state()

  + Editor_state.lines = load_array{'abc', 'def'}

  + Editor_state.screen_top1 = {line=2, pos=1}

  + Editor_state.cursor1 = {line=2, pos=1}

  + Text.redraw_all(Editor_state)

  + -- backspace scrolls up

  + edit.run_after_keychord(Editor_state, 'backspace')

  + check_eq(#Editor_state.lines, 1, 'F - test_backspace_from_start_of_final_line/#lines')

  + check_eq(Editor_state.cursor1.line, 1, 'F - test_backspace_from_start_of_final_line/cursor')

  + check_eq(Editor_state.screen_top1.line, 1, 'F - test_backspace_from_start_of_final_line/screen_top')
• replacement in text.lua at line 209
  [3.2866]→[3.2455:2510](∅→∅)
  − if Text.lt1(State.cursor1, State.screen_top1) then
  [3.2866]

  [2.3]
  + if State.screen_top1.line > #State.lines then

  + Text.populate_screen_line_starting_pos(State, #State.lines)

  + local line_cache = State.line_cache[#State.line_cache]

  + State.screen_top1 = {line=#State.lines, pos=line_cache.screen_line_starting_pos[#line_cache.screen_line_starting_pos]}

  + elseif Text.lt1(State.cursor1, State.screen_top1) then