Follows and relationships (#27)

* Follows -- create and undo, both remote and local
* Statuses -- federate new posts, including media, attachments, CWs and image descriptions.

internal/gtsmodel/messages.go

@@ -9,9 +9,11 @@ package gtsmodel
 
 // FromClientAPI wraps a message that travels from client API into the processor
 type FromClientAPI struct {
-	APObjectType   ActivityStreamsObject
-	APActivityType ActivityStreamsActivity
+	APObjectType   string
+	APActivityType string
 	GTSModel       interface{}
+	OriginAccount  *Account
+	TargetAccount  *Account
 }
 
 // // ToFederator wraps a message that travels from the processor into the federator
@@ -23,7 +25,8 @@ type FromClientAPI struct {
 
 // FromFederator wraps a message that travels from the federator into the processor
 type FromFederator struct {
-	APObjectType   ActivityStreamsObject
-	APActivityType ActivityStreamsActivity
-	GTSModel       interface{}
+	APObjectType     string
+	APActivityType   string
+	GTSModel         interface{}
+	ReceivingAccount *Account
 }