An implementation of the RIPEMD-160 cryptographic hash.
First create a Ripemd160 object using the Ripemd160 constructor,
then feed it input using the input or input_str methods, which
may be called any number of times.
After the entire input has been fed to the hash read the result using
the result or result_str methods.
The Ripemd160 object may be reused to create multiple hashes by
calling the reset method.