Escaped ,'s in sets and vectors were unescaped before tokenization
Handling of zero-length-strings as last element in a set was broken (sets ending with a ,).
Hashing of lines just containing zero-length-strings was broken (now a \0 is appended to each
string before it is hashed - giving us a hash of something for a line just consisting of \0s.
This also allows to differentiate between vectors with varying numbers of zero-length-strings).
