Documentatening.
Added "wasCached" field to TradeInternalInventory class.
Possibility of loading previously saved backpacks?
Added notes to specific details when from the official API.
Made TF2Item an inner class.
No apparent reason, though I figure if WebAPI integration happens, the AssetBuilder can provide it to the inner class.
Merge branch 'master' of https://github.com/nosoop/SteamTrade-Java.git