KT-2601 Don't display "Original: null" in quick info

Added resolving within libraries if BindingContext didn't provide declaration.
If text for 'Original' is null then second row will not be displayed.

In `org.jetbrains.jet.plugin.JetQuickDocumentationProvider#isKotlinDeclaration` I am using `org.jetbrains.jet.plugin.references.StandardLibraryReferenceResolver` for resolving declaration of a link - think this is most convenient way to do this. But since `originalElement` is a Reference(maybe not in all cases, but I didn't find when not) we can obtain declaration directly from this reference(`resolve()`) - I think this will be much faster and precisely, since in general resolver return collection and I didn't know another way of showing first of it. 
What you suggest in this case?