named iterator classes for map classes on as3, swf, C#, Neko

This is a test version of using real classes as iterators for all of the map types across as3, swf, C#, neko. It changes the ds.Map type to use the new specific named iterator types, which can't really occur until all of the targets have this work done for them. We could start by having it still use Iterator instead of the classnames though, and add that later, or we could finish porting the Map code for the other targets. (Java is almost identical to C# and PHP should be almost the same as neko, which doesn't leave much left)

Also, please note that it seems that the existing WeakMap and ObjectMap did not work on AS3 tho they worked on SWF output (due to needing a Dynamic class). This is corrected in this version.