Nuget Migration
Update build.sh to be executable on CI server
Build subprojects
Remove targets
Attempt nuget package restore (with retry)

(With thanks to SteamKit2's developers)
Adding in missing SolutionDirParsed
Missing using
Another try to fix the ClientMsgProtobuf error in CI builds
Prevent the trade from crashing when an out-of-schema item is added

Fixes #390
When merged with #405, this will supersede #393.

Also fixes a copy paste error in #393 in the FireOnUserRemoveItem function.
Set protobuf to use package version that Steamkit2 was compiled with (2.0.0.621)
Code style changes
Autodownload NuGet.exe on build in VS.

This commit will work on Windows machines. Still looking for a fix for Mono

[ci skip]
Remove NuGet.exe from sln
Removes todos and prints to console
Download nuget.exe
Download to the correct directory
Adds "exec" command and other BotManager tweaks.

Allows commands to be given directly to bots via the BotManager
console.This command is handled in the UserHandler's `OnBotCommand`.

Other changes include threading the BotManager commands and
slightlychanging the way accounts are authorized while
`UseSeparateProcesses  = true`.

Extended functionality of the "start", "stop", and "auth" commands to
allow usernames as well as indexes.

Also fixed the `Console.Title` being set to the last bot to be
configured while in Separate Processes mode.
Readme update to include information about the subreddit
Updates to force Mono3
Add appropriate flags to apt commands