More tests!

[leeper]

• `%unf% equivalence operator

• print method

• dispatch to old versions (3, 4, 4.1, 5, error otherwise)

• raw vectors:

  Normalize bit fields by converting to big-endian form, truncating all leading empty bits, aligning to a byte boundary by padding with leading zero bits, and base64 encoding to form a character string representation.

• dates

• datetimes

• difftimes

• character encoding

Note: some of these are carried forward from #2.