added _.assign/_.extend definitions
fixed tests for _.assign/_.extend, removed old tests for _.extend
added _.clone defintions
added _.cloneDeep definitions
added _.defaults definitions, removed duplicate _.extends definition
added _.findKey definitions
added _.findLastKey definitions
added _.forIn definition
added _.forInRight definition
added _.forOwn definitions
added _.forOwnRight definitions
added _.functions/_.methods definitions
added _.has definition
removed duplicate tests
added _.invert definition
Added missing type castings in tests
added _.isArguments definition
added _.isArray definition
added _.isDate definition
added _.isElement definition