Parsing UTF-8 in changes (bytes vs chars)

Dependencies

• [2] OXMYGLW2 Printing the actual lines rather than str::lines + \n
• [3] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).

Change contents

• replacement in libpijul/src/change.rs at line 2499
  [2.67]→[2.67:142](∅→∅)
  − while let Some(n) = contents.chars().position(|c| c == '\n') {
  [2.67]

  [2.142]
  + while let Some(n) = contents.as_bytes().iter().position(|&c| c == b'\n') {