Add a changelog entry about changes in Array helper's element() and elements()
config->item() now returns NULL instead of FALSE when the required item doesn't exist.

Uniformization with other functions. This also brings the ability to properly use booleans in configuration.
Adjustments to the previous commit
Uniformize slash_item() with item()
Merge pull request #2565 from vlakoff/develop

Form helper: refactor form_open() and _attributes_to_string()
Merge pull request #2554 from vlakoff/develop-3

config->item() now returns NULL instead of FALSE when the required item doesn't exist.
Complete 3.0 upgrade notes about NULL returned on missing items