API and build change and fix summaries. Doc correctsions
and/or changes are not mentioned here; see the commit messages.
+2020 February 14; version 3.1.3
+ Fix bug in SIsend which was causing a core dump in some cases
+ where the application attempted to send on a connection that
+ had disconnected. (RIC-207).
+
2020 February 6; version 3.1.2
Fix disconnection detection bug in interface to SI95.