Update ChangeLog, AUTHORS and issues_closed_for_0.18.md for an upcoming 0.18 release.

AUTHORS

@@ -1,4 +1,5 @@
 Alan Coopersmith <alan.coopersmith@oracle.com>
+Alan Urmancheev <108410815+alurm@users.noreply.github.com>
 Alexander Dahl <post@lespocky.de>
 Alexandru Ardelean <ardeleanalex@gmail.com>
 An7ar35 <eadavison@protonmail.com>
@@ -6,6 +7,7 @@ andy5995 <andy400-dev@yahoo.com>
 Aram Poghosyan <Aram.Poghosyan@teamviewer.com>
 Björn Esser <besser82@fedoraproject.org>
 BonsaY <bonsay@posteo.de>
+Bruno Haible <bruno@clisp.org>
 changyong guo <guo1487@163.com>
 chenguoping <chenguopingdota@163.com>
 Chris Lamb <lamby@debian.org>
@@ -21,9 +23,12 @@ dota17 <chenguopingdota@163.com>
 Eric Haszlakiewicz <erh+git@nimenees.com>
 Eric Hawicz <erh+git@nimenees.com>
 Even Rouault <even.rouault@spatialys.com>
+evo <149657734+evo-i@users.noreply.github.com>
+Fabrice Fontaine <fontaine.fabrice@gmail.com>
 Federico Francescon <federico.francescon@higeco.com>
 Gianluigi Tiesi <sherpya@netfarm.it>
 grdowns <grdowns@microsoft.com>
+HansolChoe <hansol614@gmail.com>
 Hex052 <elijahiff@gmail.com>
 hofnarr <hofnarr@hofnarr.fi>
 ihsinme <61293369+ihsinme@users.noreply.github.com>
@@ -51,6 +56,7 @@ Micah Snyder <micasnyd@cisco.com>
 Michael Clark <michael@metaparadigm.com>
 myd7349 <myd7349@gmail.com>
 Pascal Cuoq <cuoq@trust-in-soft.com>
+Pavel Zwerschke <pavelzw@gmail.com>
 Pawday <pawday@mail.ru>
 Philosoph228 <philosoph228@gmail.com>
 Pierce Lopez <pierce.lopez@gmail.com>
@@ -58,7 +64,9 @@ Po-Chuan Hsieh <sunpoet@sunpoet.net>
 Ramiro Polla <ramiro.polla@gmail.com>
 Rikard Falkeborn <rikard.falkeborn@gmail.com>
 Robert Bielik <robert.bielik@dirac.com>
+Robert Pang <robertpang@google.com>
 Robert <roby_p97@yahoo.com>
+Rolf Eike Beer <eb@emlix.com>
 Rosen Penev <rosenp@gmail.com>
 Rubasri Kalidas <rubasri.kalidas@intel.com>
 Sergey Sharshunov <s.sharshunov@gmail.com>