support a commandline arg just like in pensieve.love

Dependencies

• [2] XKE4KC65 Merge upstream
• [3] 3HIZXZI7 Merge lines.love
• [4] CV6XLZMW trailing slash on directory
• [5] QZ2SXLHF some debug prints
• [6] ZJOSQFN6 bugfix: path munging on Windows
• [7] UHB4GARJ left/right margin -> left/right coordinates
• [8] TGZAJUEF bring back a set of constants
• [9] 2L5MEZV3 experiment: new edit namespace
• [10] LF7BWEG4 group all editor globals
• [11] 57OGXVHZ Merge lines.love
• [12] MSDHRXWU Merge upstream into main
• [13] KKMFQDR4 editing source code from within the app
• [*] FS2ITYYH record a known issue

Change contents

• replacement in run.lua at line 25
  [4.178636]→[4.15:35](∅→∅)
  − assert(#arg == 0)
  [4.178636]

  [4.35]
  + -- '/' should work even on Windows
• replacement in run.lua at line 27
  [4.91]→[4.91:164](∅→∅)
  − Editor_state.filename = Editor_state.directory..Editor_state.file_path
  [4.91]

  [4.164]
  + local base_dir = dirname(love.filesystem.getSaveDirectory())

  + if #arg == 0 then

  + Editor_state.directory = 'pensieve/data/'

  + else

  + Editor_state.directory = 'pensieve/data.'..arg[1]..'/'

  + end

  + Editor_state.filename = base_dir..Editor_state.directory..Editor_state.file_path
• replacement in edit.lua at line 97
  [4.3539]→[3.26:141](∅→∅)
  − directory = dirname(love.filesystem.getSaveDirectory())..'pensieve/data/', -- '/' should work even on Windows
  [4.3539]

  [4.343]
  + directory = nil,
• edit in README.md at line 21
  [2.133]

  [2.133]
  + If you invoke pensieve with an additional arg (see its docs), you can also

  + pass it in to capture.