create space for app-specific settings

Dependencies

• [2] WZZGVKSG a few more renames
• [3] DSDKFEUK persist window geometry to disk across restart
• [*] OTIBCAUJ love2d scaffold
• [*] MPETAKZ2 insert space for loading settings
• [*] 5OVKHVY6 nice way to make on.* handlers more discoverable

Change contents

• edit in main.lua at line 65
  [3.248]

  [3.248]
  + app = on.save_settings and on.save_settings(),
• edit in main.lua at line 81
  [3.747]

  [6.51]
  + if on.load_settings then on.load_settings(settings.app) end
• edit in 0001-on at line 18
  [2.588]

  [7.557]
  + -- on.load_settings(settings) -- fan out settings table into any other global state

  + -- on.save_settings() -- return a settings table which will be persisted to disk across restart