feat: dag-jose implementation using IPLD schema/code generation (#23)

* feat: `dag-jose` implementation using IPLD schema/code generation

* cleanup

* support for "flattened" JOSE objects

* updates from review

* comments and renaming

* validate (then ignore) `link` when encoding

* updates and test fixes

* first pass of unit tests

* update dependencies

* test fixes

* Introduce tests using fixtures from the ipld/ipld repo. (#24)

* Introduce tests using fixtures from the ipld/ipld repo.

* tweak some fixture hunk names.

See commit message in the linked commit in the ipld/ipld submodule.

(Calling both the dagjose and the dagjson hunks "data", as it was
previously, suggested incorrect things: they are not that similar.
The dagjson is the datamodel view, and that is *not* the same thing
as a transliteration of the tokens that you'd get if you parsed the
dag-jose as dag-cbor.)

* test fixes

* test fixes

* test fixes

* test fixes

* cleanup docs

* remove `link` from encoded JWS

* fix up tests

* minor updates and add TODOs

* add CID matching to spec tests

* remove travis.yml file and add TODOs to README.md

* Update spec_test.go

Remove redundant code

* updates from review

* update to latest ipld repo

* use newest go-ipld-prime

* check err from traversal

Co-authored-by: Eric Myhre <hash@exultant.us>

.gitmodules

@@ -0,0 +1,3 @@
+[submodule ".ipld"]
+	path = .ipld
+	url = https://github.com/ipld/ipld/

README.md

@@ -1,62 +1,14 @@
 # go-dag-jose
 
-An implementation of the [`dag-jose`](https://github.com/ipld/specs/pull/269) multiformat for Go. 
+This is an implementation of the IPLD [dag-jose codec](https://ipld.io/specs/codecs/dag-jose/spec/).
 
-## Example usage
+Data that is encoded using the `dag-jose` codec is guaranteed to be a CBOR encoding of the general serialization of
+either a JWE or a JWS.
 
-To read a JWS from IPFS:
+Module initialization registers the `dagjose.Encode` and `dagjose.Decode` with `go-ipld-prime`.
 
-```go 
-import ( 
-    "github.com/alexjg/dagjose" cidlink "github.com/ipld/go-ipld-prime/linking/cid"
-)
-// Here we're creating a `CID` which points to a JWS
-jwsCid, err := cid.Decode("some cid")
-if err != nil {
-    panic(err)
-}
-// cidlink.Link is an implementation of `ipld.Link` backed by a CID
-jwsLnk := cidlink.Link{Cid: jwsCid}
+## TODOs
 
-ls := cidlink.DefaultLinkSystem()
-
-jose, err := dagjose.LoadJOSE(
-    jwsLnk,
-    ipld.LinkContext{},
-    ls, //<an implementation of ipld.Loader, which knows how to get the block data from IPFS>,
-)
-if err != nil {
-    panic(err)
-}
-if jose.AsJWS() != nil {
-    // We have a JWS object, print the general serialization of it
-    print(jose.AsJWS().GeneralJSONSerialization())
-} else {
-    print("This is not a JWS")
-}
-```
-
-To write a JWS to IPFS
-
-```go
-dagJws, err := dagjose.ParseJWS([]byte("<the general JSON serialization of a JWS>"))
-if err != nil {
-    panic(err)
-}
-ls := cidlink.DefaultLinkSystem()
-link, err := dagjose.StoreJOSE(
-    ipld.LinkContext{},
-    dagJws.AsJOSE(),
-    ls,
-)
-if err != nil {
-    panic(err)
-}
-fmt.Printf("Link is: %v", link)
-```
-
-## Changelog
-
-This project attempts to stay up to date with changes in `go-ipld-prime`, this
-means somewhat frequent API breakage as `go-ipld-prime` is not yet stable. 
-See [the changelog](./CHANGELOG.md).
+- [ ] Add support for "compact" JWE/JWS serialization
+- [ ] Add CI pipeline
+- [ ] Add support for comparing recursive types in unit tests