Minor add version mangement recommendation to README
Add inline documentation to idempotent public method
Add inline documentation to idempotent accessor methods

Minor fix missing access policy
Add inline doc. to cryptographically critical method
Minor fix obsolete inline documentation
Minor remove obsolete dependency requirement

I forgot to remove it when I removed a deprecated Cucumber hack,
see 21ee5ed7dbb0701cffd84a12215937cdb19ae4f8 and #104