labelarray testing
This release includes the new labelarray data type and compressed label block support.
- Adds first-pass support for labelarray data type that combines labelblk and labelvol
- Includes compressed label blocks via common/labels, used in some labelarray ops at this time like fast RLE generation. Internal DVID label compression is a variable compression version of the Google Neuroglancer technique. This format is only supported currently under labelarray datatype.
- Improves Google Cloud Storage support via the storage/gbucket package.