Stub is an attribute which specifies that if a symbol is ever used, Needs should automatically be called on the context of the symbol.
Symbols with the Stub attribute are created by DeclarePackage.
A symbol is considered "used" if its name appears explicitly, not in the form of a string.
Names["nameform"] and Attributes["nameform"] do not constitute "uses" of a symbol.
See Section 2.6.3 and Section 2.7.11.
New in Version 2.