Changing the default filters for ignored files

Dependencies

• [2] OJZWJUF2 MUCH faster `pijul add -r`
• [3] 4OCC6D42 Recursive add
• [4] ZHABNS3S Canonicalize all paths
• [*] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in libpijul/src/working_copy/filesystem.rs at line 153
  [2.1195]→[2.1195:1291](∅→∅)
  − walk.standard_filters(true);

  − walk.threads(threads - 1);
  [2.1195]

  [2.1291]
  + walk.ignore(true).git_ignore(true).threads(threads - 1);