update some documentation

Dependencies

• [2] BOFNXP5G clicking now moves the cursor even on long, wrapped lines
• [3] VVXVV2D2 change data model; text can now have metadata
• [4] JCSLDGAH beginnings of support for multiple shapes
• [5] AD34IX2Z couple more tests
• [6] 6LJZN727 handle chords
• [7] AVTNUQYR basic test-enabled framework
• [*] OTIBCAUJ love2d scaffold

Change contents

• replacement in main.lua at line 19
  [3.66]→[3.66:104](∅→∅),[3.104]→[2.1677:1787](∅→∅)
  − -- mode = 'text'

  − -- string data

  − -- screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line
  [3.66]

  [3.104]
  + -- mode = 'text',

  + -- string data,

  + -- a (y) coord in pixels (updated while painting screen),

  + -- some cached data that's blown away and recomputed when data changes:

  + -- fragments: snippets of rendered love.graphics.Text, guaranteed to not wrap

  + -- screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line