Asset.prototype.unload: Get the outgoing relations via the getter instead of accessing _outgoingRelations directly. Fixes unloading of assets that have had outgoing relations removed since they were initially populated.
Asset.prototype.unload: Get the outgoing relations via the getter instead of accessing _outgoingRelations directly. Fixes unloading of assets that have had outgoing relations removed since they were initially populated.

jscinoz/assetgraph,jscinoz/assetgraph,papandreou/assetgraph,papandreou/assetgraph,papandreou/assetgraph,assetgraph/assetgraph,jscinoz/assetgraph,slang800/assetgraph,slang800/assetgraph