Update 0.86 release notes
Fix unnesting array<row> and map<row>
Respect includeCoordinator flag when scheduling randomly
[maven-release-plugin] prepare release 0.86
[maven-release-plugin] prepare for next development iteration
Flatten developer guide sections
Implement PrestoConnection.getTransactionIsolation

Resolves #2031
Fix ArrayIndexOutOfBoundsException when parsing Hive timestamp column
Simplify example code for isNull function
Require Java 8