v2.3.0 (update)

change (RLP object) Notation to use square brackets and single quotes;
move KeyValuePair and Record into rlp package, make the associated RLP util methods package-private;
RLPEncoder.encodeSequentially no longer accepts arrays of KeyValuePair;
for TupleType.decode(byte[]), throw IllegalArgumentException if there are unconsumed trailing bytes;
make some classes final;
add WrappedKeccak which wraps bouncycastle impl -- org.bouncycastle:bcprov-jdk15on:1.64 is now a dependency;
add Tuple serializer/deserializer SuperSerial;
add method Function.parse(String, MessageDigest);

SHA-256 (headlong-2.3.0.jar): 54911021447e580337d2b04aa8fcbb1e2abe076e8da77677392ee0307fb5f15b