Add a README.md with API documentation

Also fix some smaller issues found during writing the documentation

briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt

@@ -7,6 +7,7 @@ import io.javalin.apibuilder.ApiBuilder.*
 import io.javalin.core.util.ContextUtil
 import io.javalin.core.util.Header
 import org.briarproject.briar.headless.blogs.BlogController
+import org.briarproject.briar.headless.contact.ContactController
 import org.briarproject.briar.headless.forums.ForumController
 import org.briarproject.briar.headless.messaging.MessagingController
 import java.lang.Runtime.getRuntime
@@ -22,7 +23,7 @@ class Router @Inject
 constructor(
     private val briarService: BriarService,
     private val webSocketController: WebSocketController,
-    private val contactController: MessagingController,
+    private val contactController: ContactController,
     private val messagingController: MessagingController,
     private val forumController: ForumController,
     private val blogController: BlogController

briar-headless/src/main/java/org/briarproject/briar/headless/blogs/BlogController.kt

@@ -28,7 +28,7 @@ constructor(
                 val body = blogManager.getPostBody(header.id)
                 header.output(body)
             }
-        }
+        }.sortedBy { it.timestampReceived }
         return ctx.json(posts)
     }
 

briar-headless/src/main/java/org/briarproject/briar/headless/contact/OutputContact.kt

@@ -7,12 +7,12 @@ import javax.annotation.concurrent.Immutable
 
 @Immutable
 internal data class OutputContact(
-    val id: Int,
+    val contactId: Int,
     val author: OutputAuthor,
     val verified: Boolean
 ) {
     internal constructor(c: Contact) : this(
-        id = c.id.int,
+        contactId = c.id.int,
         author = c.author.output(),
         verified = c.isVerified
     )

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingControllerImpl.kt

@@ -47,7 +47,7 @@ constructor(
                     header.output(contact.id, body)
                 }
             }
-        }
+        }.sortedBy { it.timestamp }
         return ctx.json(messages)
     }