feat(scripts): robust authors.sh

- Determine the latest two semver release tags by sorting them.
- Dedupe author names using BOTH their e-mail address and their name.
  This ensures that the following two entries dedupe into one.
  - Matias Niemelä (Matias Niemela\xcc\x88)
  - Matias Niemelä (Matias Niemel\xc3\xa4)

Closes #586

scripts/changelog/authors.sh

@@ -2,4 +2,23 @@
 
 LAST_TAG=`git tag | grep ^v | tail -n1`
 
-git log v0.9.3..HEAD | grep Author | sort | uniq | sed 's/Author: \(.*\) \<.*/\1/' | tr "\\n" ", " | sed 's/,$/\n/' | sed 's/\,/, /g'
+# Determine the lastest two versions sorting the semvers correctly.
+REV_RANGE=$(git tag -l | python -c '
+import sys, re
+version_re = re.compile(r"^(.*/)?(v[0-9.]+)$")
+key = lambda m: tuple(map(int, m.group(2)[1:].split(".")))
+matches = sorted(dict(
+    (key(m), m) for m in map(version_re.search, sys.stdin) if m).items())
+print "%s..%s" % (matches[-2][1].group(0), matches[-1][1].group(0))
+')
+
+echo $REV_RANGE
+
+# Canonicalize by BOTH e-mail address and by name.
+# e.g. Matias Niemelä (Matias Niemela\xcc\x88) and
+#      Matias Niemelä (Matias Niemel\xc3\xa4) are the same.
+git log --pretty=tformat:'%ae %an' "$REV_RANGE" | python -c '
+import sys
+authors = set(dict(line.split(" ", 1) for line in sys.stdin).values())
+print ", ".join(sorted(authors)).replace("\n", "")
+'