Mantle/Mantle — pull request #311 by kilink (2014-04-18 00:32:44+00:00)
Title: make mergeValuesForKeysFromModel: work with sub classes

This PR changes MTLModel's mergeValuesForKeysFromModel: method to only merge values for keys that are present in both the target model and the passed in source model.

This allows scenarios such as passing in a subclass to only update certain keys on the target model.

See issue #307 for discussion.