fold variables for screen dimensions into the app framework

Dependencies

• [2] AVTNUQYR basic test-enabled framework
• [3] 2RXZ3PGO beginning of a new approach to scroll+wrap
• [4] 2C7CTIQY make space for multiple kinds of width
• [5] DLQMM265 scroll past first page
• [6] JVRL5TWL store device-independent coordinates inside drawings
• [7] V5TP27FP ctrl-+ and ctrl-- to adjust font size
• [8] ZNLTRNNK highlight another global
• [9] JCSLDGAH beginnings of support for multiple shapes
• [10] 242L3OQX bugfix: ensure Cursor_line is always on a text line
• [11] AVQ5MC5D finish uppercasing all globals
• [12] ESETRNLB bugfix: printing the first part of a line at the bottom made it seem non-wrapping
• [13] OTIBCAUJ love2d scaffold
• [14] Y6FTGOHJ simpler
• [15] UWNHC4AA redo y computations
• [16] HDC3AAQP silly reason my screenshots had an ugly black line down the left
• [17] XX7G2FFJ intermingle freehand line drawings with text
• [18] 7IKRRESB longer names for indices in long loops
• [19] OIB2QPRC start remembering where the cursor is drawn in px
• [20] DXT4QTAH a few more integer coordinates
• [21] 2POFQQLW keep cursor on screen when pressing 'down'

Change contents

• replacement in main.lua at line 66
  [2.973]→[2.973:1039](∅→∅)
  − Screen_width, Screen_height, Screen_flags = love.window.getMode()
  [2.973]

  [2.1039]
  + App.screen.width, App.screen.height = love.window.getMode()
• replacement in main.lua at line 68
  [2.1091]→[2.1091:1206](∅→∅)
  − Screen_width = Screen_width-100

  − Screen_height = Screen_height-100

  − love.window.setMode(Screen_width, Screen_height)
  [2.1091]

  [3.54]
  + App.screen.width = App.screen.width-100

  + App.screen.height = App.screen.height-100

  + love.window.setMode(App.screen.width, App.screen.height)
• replacement in main.lua at line 78
  [2.1272]→[2.1272:1318](∅→∅)
  − Line_width = math.floor(Screen_width/2/40)*40
  [2.1272]

  [3.1]
  + Line_width = math.floor(App.screen.width/2/40)*40
• replacement in main.lua at line 117
  [3.243]→[3.859:932](∅→∅)
  − love.graphics.rectangle('fill', 0, 0, Screen_width-1, Screen_height-1)
  [3.243]

  [3.302]
  + love.graphics.rectangle('fill', 0, 0, App.screen.width-1, App.screen.height-1)
• replacement in main.lua at line 126
  [3.2072]→[3.161:223](∅→∅),[3.44]→[3.161:223](∅→∅)
  − if y + math.floor(15*Zoom) > Screen_height then break end
  [3.2072]

  [3.9247]
  + if y + math.floor(15*Zoom) > App.screen.height then break end
• replacement in main.lua at line 236
  [3.1796]→[3.1796:1824](∅→∅)
  − local y = Screen_height
  [3.1796]

  [3.1824]
  + local y = App.screen.height