Display a message box when the user tries to assign a limit trait twice

Currently, if a user assigns to an attribute A a limit trait that is already used by another attribute B under the same parent attribute, then attribute A will gain the limit trait and attribute B will silently lose the limit trait. Silent changes that affect how the PI Asset Framework works are never a good thing. Consider displaying a message box in PI System Explorer if the user tries to assign a previously assigned limit trait. For example, "The Target limit trait is already assigned to attribute B. Do you want to remove the Target limit trait from attribute B and assign it to attribute A?". PI Builder should refuse, with an error message, to publish changes that involve duplicate limit trait assignment.