Parsing the correct flags for new vertices

Dependencies

• [2] 73NW2X2M Returning a parse error instead of panicking when parsing a text change
• [3] L5PHFTIE Minor simplification
• [4] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).
• [5] UBCBQ5FG Removing pijul/src/commands/checkout.rs (unused file), as well as litorg comments
• [*] VO5OQW4W Removing anyhow in libpijul

Change contents

• replacement in libpijul/src/diff/delete.rs at line 176
  [3.810948]→[3.810948:810997](∅→∅)
  − flag: previous | EdgeFlags::DELETED,
  [3.810948]

  [3.810997]
  + flag: previous | EdgeFlags::BLOCK | EdgeFlags::DELETED,
• edit in libpijul/src/change/text_changes.rs at line 599
  [2.180]

  [7.61137]
  + v.flag = EdgeFlags::BLOCK;
• edit in libpijul/src/change/text_changes.rs at line 616
  [2.233]

  [7.61724]
  + v.flag = EdgeFlags::BLOCK;