Add simple login test with online friends. Add IFriendsModule.GrantRights() for granting rights via a module call.

Rename IFriendsModule.GetFriendPerms() -> GetRightsGrantedByFriend() to be more self-documenting and consistent with friends module terminology.
Add some method doc.

OpenSim/Services/Interfaces/IFriendsService.cs

@@ -36,7 +36,15 @@ namespace OpenSim.Services.Interfaces
     {
         public UUID PrincipalID;
         public string Friend;
+
+        /// <summary>
+        /// The permissions that this user has granted to the friend.
+        /// </summary>
         public int MyFlags;
+
+        /// <summary>
+        /// The permissions that the friend has granted to this user.
+        /// </summary>
         public int TheirFlags;
 
         public FriendInfo()