RFR: 715: Generated email wrongly includes previous unrelated comments

[Robin Westberg]

When selecting a parent for a new comment, use the last revision email as parent if no quote / mention is found, as just using the latest one can be confusing if that's not really the intended context.

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Commit messages:
 - Use last revision email as parent if no quote / mention is found

Changes: https://git.openjdk.java.net/skara/pull/1108/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1108&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-715
  Stats: 31 lines in 2 files changed: 12 ins; 8 del; 11 mod
  Patch: https://git.openjdk.java.net/skara/pull/1108.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1108/head:pull/1108

PR: https://git.openjdk.java.net/skara/pull/1108