More tweaks to web json line_breaks indices

- The last value of line_break range seems to not be included?  By
- setting max index "too high" we get expected behaviour at
  discontinuities.
- Gamma-point LO-TO split still looks wrong, fix that separately?

euphonic/qpoint_phonon_modes.py

@@ -888,8 +888,8 @@ def _to_phonon_website_dict(self,
         duplicates = self._expand_duplicates(abscissa)
         breakpoints = self._remove_breaks(abscissa)
 
-        breakpoints = sorted(set([-1] + duplicates + breakpoints + [len(abscissa)]))
-        line_breaks = [(start + 1, end) for start, end in pairwise(breakpoints)]
+        breakpoints = sorted(set([-1] + duplicates + breakpoints + [len(abscissa) - 1]))
+        line_breaks = [(start + 1, end + 1) for start, end in pairwise(breakpoints)]
 
         if x_tick_labels is None:
             x_tick_labels = get_qpoint_labels(qpts,