Changelog for model-0.4.1

Significant and compatibility-breaking changes. Version 0.4: - Data.Model.Types: - Modified type of 'constructors' and 'constructorInfo' - Removed instances of StringLike (replaced with Convertible) - Modified behaviour of conversion from String to QualName - Data.Model.Util: - modified type of 'mutualGroups' and 'transitiveClosure' Version 0.3: - Data.Model.Util: - Removed 'dependencies' - Added the (similar but not identical) function 'transitiveClosure'