Give better error messages from Trade.Poll(), use an enum for trade_status
On trade_status == 2, retry the request later
Correctly set _otherUserTimingOut
(I'm not sure what happened to this code, I'm 100% I wrote it...)
Renaming private fields to keep code-style consistent
Merge branch 'JessecarMaster' into TradeErrorImprovements

Conflicts:
	SteamBot/UserHandler.cs
Added fix for ItemAdded/Removed events sometimes being delayed; also added some basic safety checks.
BUGFIX: OnUserAddItem is sometimes called twice for one item... :|
Adding changes suggested by Husky (Scholtz)
Merge pull request #632 from BlueRaja/AddItemCallbackDelayed

Added fix for ItemAdded/Removed events sometimes being delayed
Merge branch 'JessecarMaster' into TradeErrorImprovements

Conflicts:
	SteamTrade/Trade.cs
Merge pull request #615 from BlueRaja/TradeErrorImprovements

Better error-messages for trades