Improved alias handling for named scopes
* Moved AbstractUse.FindMatches() to a new AbstractScopeUse class (MethodCall, NamedScopeUse, and TypeUse are now children of AbstractScopeUse)
* Moved code for finding the relevant namespace for an alias to the Alias class
* AbstractCodeParser adds aliases to method calls when there is no calling object
* Moved TypeUse.AddAlias(es) to AbstractUse
* Simplified LINQ query in VariableUse.FindMatchingTypes()
* Fixed alias in type inventory test