Attach cause to ComException on Client.start

This is to enable more investigation of a rare flaky failure of IndexOperationsIT.
Revert "Debug logging of cluster members state"

This reverts commit 89f93d3c986efe18574bb353453195893f8f0b9e.
Add missing entry for import in manpage list.
Merge pull request #3559 from chrisvest/2.2-indexops-it

Attach cause to ComException on Client.start
Merge pull request #3566 from lutovich/2.2-remove-debug-logging

Revert "Debug logging of cluster members state"
Merge pull request #3572 from nawroth/import-manpage

Add missing entry for import in manpage list.
Revert "Revert "Lock-free loading of relationships""

This reverts commit 11913455f8cbab4d601e72b4d4d3f08095e3e6ed.

I.e. it's a re-revert, hence a re-commit of
7bb2861dee3d0018a4e75c84841c8b71f818d6b9
Adding terminology section.