crypto/tls: replace custom equal implementations with reflect.DeepEqual
The equal methods were only there for testing, and I remember regularly
getting them wrong while developing tls-tris. Replace them with simple
reflect.DeepEqual calls.
The only special thing that equal() would do is ignore the difference
between a nil and a zero-length slice. Fixed the Generate methods so
that they create the same value that unmarshal will decode. The
difference is not important: it wasn't tested, all checks are
"len(slice) > 0", and all cases in which presence matters are
accompanied by a boolean.