Fast Tags

[jfphilbin]

1. Create Tag interface
   a. All VR access in terms of vrIndex
   b. All VM access in terms of min, max and columns
   c. All Semantic ID access in terms of Code (and later index)
2. Update existing Tag package to conform to new interface
3. Create FastTags package the includes all tag info in 64 bit int.
4. Update Dataset to support fast tags.