- create struct types.

- fixed class creation. There was an infinite loop and some missing checks for native classes.
- do not write the compiler's symbols to the same symbol table as the output. The output must go to GlobalSymbols but the internal symbols must go to a namespace specific table that can be discarded after compilation.

src/zscript/zcc-parse.lemon

@@ -248,6 +248,7 @@ struct_def(X) ::= STRUCT(T) IDENTIFIER(A) LBRACE opt_struct_body(B) RBRACE opt_s
 	NEW_AST_NODE(Struct,def,T);
 	def->NodeName = A.Name();
 	def->Body = B;
+	def->Type = nullptr;
 	X = def;
 }