FYI: Resolution - Build / Compile Issues - The XML namespace for the conceptual model's Schema element is not supported on this project's target framework version

Apparently when compiled w/ a 2012 vs. a 2013 it IDE (minimum known is “Premium”) it will no longer play nicely yielding many rabbit holes and a rather generic error of “The XML namespace for the conceptual model's Schema element is not supported on this project's target framework version”.