Show error for free variabless acces.
Closures will allow capturing. For now it is not possible.

During parsing variable acces check is it capturing from anonymous routine. Anonymous routine have normal nesting level and can have nested procedures itself. That is why checking of symtable nesting level is not enough. If we inside closure then from current symtable using parent link we will come to anonymous procedure symtable(with normal nesting level). If during this walking we foung symtable with accessed variable then evething is ok. Otherwise this is capture.