Small documentation update

As the error templates are now by default inside the views folder.
Make the error templates path configurable
Group error templates entries in changelog
Rename config item "error_templates_path" to "error_views_path"
Different method for handling "error_views_path" config item
Replace "folder" with "directory" in config.php
Uniformization in smiley helper documentation

oversight from 20292311636837e120d205e470e41826820feb46
Merge pull request #2999 from vlakoff/error-templates

Make the error templates path configurable