Fix: web-related crashes

Edited:
Bot.cs - BackgroundWorkerOnDoWork(...)
Added: other exceptions + restart
Improving error messages and fixing non-restarting bug
BUGFIX (to laggingpyro's stuff): Not sure what the purpose of this was, but it appears to cause an infinite loop sometimes
Adds Clan Related Handlers and Functions

What this does:
- Adds OnClanAdd() function to UserHandler.cs, SimpleUserHandler.cs, and
AdminUserHandler.cs.
- Adds InviteUserToClan() function to Bot.cs.
- Adds DeclineClanInvite() function to Bot.cs.
- Adds AcceptClanInvite() function to Bot.cs.
- Adds ClanMessages.cs that contains all SteamMessages need for new
actions.
- Filters out Clan Invites from Friend Invites.
- Adds a Clan list that contains all Clans the Bot is in.
- Fixes some spelling errors.
- Updates outdated EEconTradeResponse message types.
Renamed "Clan" to "Group," as per @geel9's request on the original pull-request
Moved group-related messages to their own folder (similar to the TF2GC folder)
Whoops!  Missed a few functions (renaming clan --> group)
Adds User Handler feedback on bot's trade request accept/decline.
Back to .NET Framework 4.0 Patch

Changed:
* Task.Run [.NET Framework 4.5] to Task.Factory.StartNew [.NET Framework
4.0]
Merge pull request #530 from BlueRaja/SteamGroupFunctions

Add functionality for Steam Groups
Merge pull request #534 from gabrielmtzcarrillo/net40

Back to .NET Framework 4.0 Patch
Removed obsolete reference to SteamKit's EChatEntryType.Emote
Merge pull request #536 from FunkyLoveCow/RemoveObsoleteWarning

Removed obsolete reference to SteamKit's EChatEntryType.Emote
Merge pull request #528 from BlueRaja/laggingPyroFixes

Keep bot running after a crash
Merge pull request #531 from FrozenHaxor/master

Adds User Handler feedback on bot's trade request accept/decline.
Bug-fix patch for #404

Surround web call with a try...catch. The exception is silently ignored but needs to be logged.

ref #394
Merge pull request #539 from cwhelchel/fix/i404

Bug-fix patch for #404
- Removed OnTradeClose(); from OnTradeAccept(); in UserHandler examples.
Timeout Fix
- this fix disables TradeManager.CheckTradeTimeout(),
after the other user accepted the trade