Codec methods are not virtual

Protected methods in Codec10 which are overridden in Codec11 and Codec12 are not virtual - therefore, the overridden ones are not called even if we use Codec12.
This causes that the L3 client cannot properly read hash function (it uses protocol version 1.2 but the computeNewHashes has to read one more VInt - it does not and the input is shifted and client gets stuck).