Bisect_ppx 1.0.1

• Add option -ignore-missing-files to bisect-ppx-report, which allows
  the reporter to silently ignore missing source files instead of
  failing. This is intended for build processes that generate temporary
  source files, but delete them before the reporter is run (requested
  Ivan Gotovchits).
• Fix bug in which bisect-ppx-report treated source code as format
  strings for Buffer.add_substitute. This caused wrong behavior on
  source code substrings that looked like Buffer.add_substitute
  patterns (reported Ivan Gotovchits).
• Various minor documentation and internal build fixes.