Fix copyright in README.
Code reorganization.

Move the SipHash-2-4 function into its own package (child package of SipHash).
SipHash is now a root package that contains the common definitions.
Implement the streaming operations.
Use streaming implementation in Hash.
Fix bug in Finalization

All tests passed.
Add a version string.
Code reorganization.

Move the tests functions into their own package (child package of Tests).
Tests is now a root package that contains the common definitions.
Fix a typo
Add tests for the streaming interface
Add Makefile
Update README.

Update the README to use the Makefile instead of gnatmake directly.
Add a target to the Makefile to run the tests.
Add 'Usage' section in README.
`Update` can now take an array of bytes.