Visitor to resolve Types and convert VariableExpression to
ClassExpressions if needed. The ResolveVisitor will try to
find the Class for a ClassExpression and prints an error if
it fails to do so. Constructions like C[], foo as C, (C) foo
will force creation of a ClasssExpression for C
Note: the method to start the resolving is startResolving(ClassNode, SourceUnit).
author: Jochen Theodorou