Issue #2311925: API change: Remove _webform_validation_all_allowed().
Issue #2312009: Improve comments for webform_validation_get_validators_selection() and webform_validation_get_validator_info().
Issue #2312019: API change: Remove _webform_validation_preg_quote() and require PHP 5.3.
Issue #1471590: Enhance someofseveral validator to allow "exactly" and "at most".
Issue #1545980: Refactor: Create and use _webform_validation_get_names_of_rule_components().
Issue #1545980: Validate sum of number components: >, >=, =, <=, <.
Issue #2312837: Allow comparison with zero.
Issue #2312837: Return array() when skipping validation.