add Permissions to Member struct (#902)

* add Permissions to Member struct

* add period to Member.Permissions comment

* change Permissions type from string to int64

structs.go

@@ -797,6 +797,9 @@ type Member struct {
 
 	// Is true while the member hasn't accepted the membership screen.
 	Pending bool `json:"pending"`
+
+	// Total permissions of the member in the channel, including overrides, returned when in the interaction object.
+	Permissions int64 `json:"permissions,string"`
 }
 
 // Mention creates a member mention