Setting up sibling and parent relationships for entries, so they can be
easier to walk.
Also, making "keyword=value" easier to parse. This helps filtering.
Both of these ready us for checking/validating a hierarchy.
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
Initially only on linux platform, but could accommodate BSDs as well.
The keyword is rather a prefix of the key. So xattr keyword will have a
prefix of "xattr." followed by a suffix of its namespace and name.
The value stored in the manifest is the SHA1 digest of the extended
attribute's data.
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
