Changes file for #20877, #20878, #20880, #20881, #20882

changes/fallbacks-201612

+  o Minor features (fallback directories):
+    - Select 200 fallback directories for each release.
+      Closes ticket 20881.
+    - Provide bandwidth and consensus weight for each candidate fallback in
+      updateFallbackDirs.py.
+      Closes ticket 20878.
+    - Require fallback directories to have the same address and port for
+      6 months. (We expect to regenerate the fallback list each major Tor
+      release.) Relays whose OnionOO stability timer is reset on restart by
+      bug 18050 should upgrade to Tor 0.2.8.7 or later, which has a fix for
+      this issue.
+      Closes ticket 20880; removes short-term fix in e220214 in
+      tor-0.2.8.2-alpha.
+    - Make it easier to change the output sort order of fallbacks.
+      Closes ticket 20822.
+  o Minor bugfix (fallback directories):
+    - Stop failing when OUTPUT_COMMENTS is True in updateFallbackDirs.py.
+      Closes ticket 20877; bugfix on commit 9998343 in tor-0.2.8.3-alpha.