Doc fix for Encryption library
Merge pull request #3017 from kakysha/develop

Doc fix for Encryption library
Fix spelling in changelog
Code adjustment in Output->set_content_type()

Suppress type juggling.
Optimization in Input->_fetch_from_array()

Also clearer, imho.
Code uniformization in Input class
Improve optional parameters handling in Input->set_cookie()

Setting them to the same values as default was overridden by global config.

For the record, one of the strict comparisons had been removed in 9ba661b02c492e89028e5c67b7edbfc0efefc9f1
Show error if "encryption_key" config item left empty
Fix possible issue in Input->set_cookie()

Fix for the case that:
- config item missing, because of outdated config.php
- and config_item() returning NULL on missing item (planned change)
Fix some typos

props @vkeranov