Will combine or write partial data of each version found in the inspect data.
Example:
```
> xl-meta -export -combine inspect-data.1228fb52.zip
(... metadata json...)
}
Attempting to combine version "994f1113-da94-4be1-8551-9dbc54b204bc".
Read shard 1 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-01-of-13.data)
Read shard 2 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-02-of-13.data)
Read shard 3 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-03-of-13.data)
Read shard 4 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-04-of-13.data)
Read shard 6 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-06-of-13.data)
Read shard 7 Data shards 9 Parity 4 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-07-of-13.data)
Read shard 8 Data shards 8 Parity 5 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-08-of-13.data)
Read shard 9 Data shards 8 Parity 5 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-09-of-13.data)
Read shard 10 Data shards 8 Parity 5 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-10-of-13.data)
Read shard 11 Data shards 8 Parity 5 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-11-of-13.data)
Read shard 13 Data shards 8 Parity 5 (994f1113-da94-4be1-8551-9dbc54b204bc/shard-13-of-13.data)
Attempting to reconstruct using parity sets:
* Setup: Data shards: 9 - Parity blocks: 6
Have 6 complete remapped data shards and 6 complete parity shards. Could NOT reconstruct: too few shards given
* Setup: Data shards: 8 - Parity blocks: 5
Have 5 complete remapped data shards and 5 complete parity shards. Could reconstruct completely
0 bytes missing. Truncating 0 from the end.
Wrote output to 994f1113-da94-4be1-8551-9dbc54b204bc.complete
```
So far only inline data, but no real reason that external data can't also be included with some handling of blocks.
Supports only unencrypted data.
Existing:
```go
type xlMetaV2 struct {
Versions []xlMetaV2Version `json:"Versions" msg:"Versions"`
}
```
Serialized as regular MessagePack.
```go
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
VersionID [16]byte
ModTime int64
Type VersionType
Flags xlFlags
}
```
Serialize as streaming MessagePack, format:
```
int(headerVersion)
int(xlmetaVersion)
int(nVersions)
for each version {
binary blob, xlMetaV2VersionHeader, serialized
binary blob, xlMetaV2Version, serialized.
}
```
xlMetaV2VersionHeader is <= 30 bytes serialized. Deserialized struct
can easily be reused and does not contain pointers, so efficient as a
slice (single allocation)
This allows quickly parsing everything as slices of bytes (no copy).
Versions are always *saved* sorted by modTime, newest *first*.
No more need to sort on load.
* Allows checking if a version exists.
* Allows reading single version without unmarshal all.
* Allows reading latest version of type without unmarshal all.
* Allows reading latest version without unmarshal of all.
* Allows checking if the latest is deleteMarker by reading first entry.
* Allows adding/updating/deleting a version with only header deserialization.
* Reduces allocations on conversion to FileInfo(s).
