0.6.4

Changes:

• tar/export: add 'state' and 'extensions' repo subdirs
• tests: Add much beefed up alternative path for test framework
• lib/src/tar/write: make sure we add the links when filtering the tar
• tests: two more small test suite patches
• tar: Add a debug function to filter tar
• cli: Use structopt's TryFrom support for parsing ostree::Repo
• tests: A few more test suite patches
• testsuite: Port to sh-inline 0.2
• tar/import: Don't crash on extant object
• tests: Factor out test fixture as a separate module
• tar/export: use full path as link target
• tar/export: export empty xattrs in v1 format
• cli: Drop use of select
• tar/v1: introduce object types for split xattrs
• container: Hard depend on skopeo copy --digestfile
• container/encapsulate: Support copying commit metadata keys
• ocidir: More direct use of direct _mut() methods