Exclude test files from main library jar file
Cosmetics
Use typed AttributeEntry objects, not just Objects for entries.

Attribute entries are a bit more complicated than I initially gave
them credit for, in particular they can be array-valued, which it
didn't look like at first glance (NumElems field has different semantics
in AEDRs than VDRs).  To handle these values sensibly, the entries
have to be represented by objects with some standard methods.
Got a bit more explicit about the way items are ordered in raw
arrays for different DataTypes too, though this is still a bit
confused/confusing.
Add note for v0.1 release