new style iterators for map classes on as3, swf, C#, neko

This is a test version (incomplete) of using real classes as iterators for all of the map types across as3, swf, C#, neko. It has some small issue in compiling nicely with TestSerialize.hx and TestBaseTypes.hx that I don't understand. 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.

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.