parse encapsulated structures (octet string or bit string containing valid ASN.1): add omitted finalCheck()
Among other things, it avoids interpreting zezo-length octet strings as encapsulated structures.
parse encapsulated structures (octet string or bit string containing valid ASN.1): reusable readString() method + let exception do its job on invalid input instead of attempt to allocate too much memory
(typeHeader.length may contain insane numbers if input in isValidBER() is not valid ASN.1/BER)