Format/WKT.js: add @requires for geometry types

I made a minimal OpenLayers build configuration file (https://gist.github.com/2936890) and noted that `OpenLayers/Geometry/MultiPolygon.js` was not pulled in.  The WKT format uses this class explicitly, so I think it should have a `@requires`  comment for it.  I'd recommend explicitly requiring all the geometry types, as in OpenLayers.Format.GML.

I'd make a pull request, but right now we're waiting on our university's legal department for word on a CLA.