StoreItemInContext() is used when you already have a pointer to the
ContextNode to which you want to attach your LCI.  It is called like so:

    StoreItemInContext (iff, lci, contextnode);

StoreItemInContext() links your LCI into the specified ContextNode.  Then
it searches the ContextNode to see if there is another LCI with the same
type, ID, and identification values.  If so, the old one is deleted.