Add support for update/delete operations on issue comments

src/main/java/org/kohsuke/github/GHIssue.java

@@ -141,8 +141,9 @@ public URL getApiURL(){
     /**
      * Updates the issue by adding a comment.
      */
-    public void comment(String message) throws IOException {
-        new Requester(root).with("body",message).to(getIssuesApiRoute() + "/comments");
+    public GHIssueComment comment(String message) throws IOException {
+        GHIssueComment r = new Requester(root).with("body",message).to(getIssuesApiRoute() + "/comments", GHIssueComment.class);
+        return r.wrapUp(this);
     }
 
     private void edit(String key, Object value) throws IOException {

src/main/java/org/kohsuke/github/GHIssueComment.java

@@ -79,4 +79,23 @@ public GHUser getUser() throws IOException {
     public URL getHtmlUrl() {
         return null;
     }
+
+    /**
+     * Updates the body of the issue comment.
+     */
+    public void update(String body) throws IOException {
+        new Requester(owner.root).with("body", body).method("PATCH").to(getCommentApiTail(), GHIssueComment.class);
+        this.body = body;
+    }
+
+    /**
+     * Deletes this issue comment.
+     */
+    public void delete() throws IOException {
+        new Requester(owner.root).method("DELETE").to(getCommentApiTail());
+    }
+
+    private String getCommentApiTail() {
+        return "/repos/"+owner.getRepository().getOwnerName()+"/"+owner.getRepository().getName()+"/issues/comments/" + id;
+    }
 }

src/main/java/org/kohsuke/github/GHPullRequestReviewComment.java

@@ -94,6 +94,7 @@ protected String getApiRoute() {
      */
     public void update(String body) throws IOException {
         new Requester(owner.root).method("PATCH").with("body", body).to(getApiRoute(),this);
+        this.body = body;
     }
 
     /**