Add Discussions API implementation (#481)

Add Discussions API implementation

gitlab.go

@@ -287,6 +287,7 @@ type Client struct {
 	CustomAttribute       *CustomAttributesService
 	DeployKeys            *DeployKeysService
 	Deployments           *DeploymentsService
+	Discussions           *DiscussionsService
 	Environments          *EnvironmentsService
 	Events                *EventsService
 	Features              *FeaturesService
@@ -426,6 +427,7 @@ func newClient(httpClient *http.Client) *Client {
 	c.CustomAttribute = &CustomAttributesService{client: c}
 	c.DeployKeys = &DeployKeysService{client: c}
 	c.Deployments = &DeploymentsService{client: c}
+	c.Discussions = &DiscussionsService{client: c}
 	c.Environments = &EnvironmentsService{client: c}
 	c.Events = &EventsService{client: c}
 	c.Features = &FeaturesService{client: c}

notes.go

@@ -45,7 +45,6 @@ type Note struct {
 		Email     string `json:"email"`
 		Name      string `json:"name"`
 		State     string `json:"state"`
-		CreatedAt *time.Time `json:"created_at"`
 		AvatarURL string `json:"avatar_url"`
 		WebURL    string `json:"web_url"`
 	} `json:"author"`
@@ -55,9 +54,37 @@ type Note struct {
 	CreatedAt    *time.Time    `json:"created_at"`
 	NoteableID   int           `json:"noteable_id"`
 	NoteableType string        `json:"noteable_type"`
+	Position     *NotePosition `json:"position"`
+	Resolvable   bool          `json:"resolvable"`
+	Resolved     bool          `json:"resolved"`
+	ResolvedBy   struct {
+		ID        int    `json:"id"`
+		Username  string `json:"username"`
+		Email     string `json:"email"`
+		Name      string `json:"name"`
+		State     string `json:"state"`
+		AvatarURL string `json:"avatar_url"`
+		WebURL    string `json:"web_url"`
+	} `json:"resolved_by"`
 	NoteableIID int `json:"noteable_iid"`
 }
 
+// NotePosition represents the "position" attributes on a note
+type NotePosition struct {
+	BaseSHA      string `json:"base_sha"`
+	StartSHA     string `json:"start_sha"`
+	HeadSHA      string `json:"head_sha"`
+	PositionType string `json:"position_type"`
+	NewPath      string `json:"new_path,omitempty"`
+	NewLine      int    `json:"new_line,omitempty"`
+	OldPath      string `json:"old_path,omitempty"`
+	OldLine      int    `json:"old_line,omitempty"`
+	Width        int    `json:"width,omitempty"`
+	Height       int    `json:"height,omitempty"`
+	X            int    `json:"x,omitempty"`
+	Y            int    `json:"y,omitempty"`
+}
+
 func (n Note) String() string {
 	return Stringify(n)
 }