Add the VIEW_AUDIT_LOG permission (#229)

src/model/permissions.rs

@@ -189,6 +189,8 @@ bitflags! {
         /// [`Message`]: ../struct.Message.html
         /// [`Reaction`]: ../struct.Reaction.html
         const ADD_REACTIONS = 0b0000_0000_0000_0000_0000_0000_0100_0000;
+        // Allows viewing a guild's audit logs.
+        const VIEW_AUDIT_LOG = 0b0000_0000_0000_0000_0000_0000_1000_0000;
         /// Allows reading messages in a guild channel. If a user does not have
         /// this permission, then they will not be able to see the channel.
         const READ_MESSAGES = 0b0000_0000_0000_0000_0000_0100_0000_0000;
@@ -291,6 +293,12 @@ impl Permissions {
     /// [Connect]: constant.CONNECT.html
     pub fn connect(&self) -> bool { self.contains(Self::CONNECT) }
 
+    /// Shorthand for checking that the set of permissions contains the
+    /// [View Audit Log] permission.
+    ///
+    /// [View Audit Log]: constant.VIEW_AUDIT_LOG.html
+    pub fn view_audit_log(&self) -> bool { self.contains(Self::VIEW_AUDIT_LOG) }
+
     /// Shorthand for checking that the set of permissions contains the
     /// [Create Invite] permission.
     ///