Added fix for ItemAdded/Removed events sometimes being delayed; also added some basic safety checks.
BUGFIX: OnUserAddItem is sometimes called twice for one item... :|
Merge branch 'AddItemCallbackDelayed'

Conflicts:
	SteamTrade/Trade.cs
Changed Quality from string to int
Removed un-used csproj file
Updated Packages
Adding changes suggested by Husky (Scholtz)
Merge branch 'nitpicks'
Merge pull request #634 from WildCard65/nitpicks

Nitpicks
Merge branch 'AddItemCallbackDelayed'

Conflicts:
	SteamTrade/Trade.cs
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
Merge branch 'JessecarMaster' into WebAndForeignInvImprovements

Conflicts:
	SteamBot/UserHandler.cs
	SteamTrade/Trade.cs
Support compression and caching on all web requests
Merge branch 'WebAndForeignInvImprovements'

Conflicts:
	SteamTrade/Trade.cs