Project file refactor (#819)

* Project file refactor

Move all the .csproj files to the new .NET Core style.
This doesn't make any difference for compiling for Framework,
but it does reduce a ton of useless boilerplate.

As an extension of this, killed a bunch of uncompiled & unmaintained .cs files.

Compiling for release (to profile) works now.
Removed AnyCPU targets from the solution file.

* Fix compiler warnings.

Robust.Server/Console/ConGroupController.cs

@@ -16,10 +16,12 @@ namespace Robust.Server.Console
     /// </summary>
     internal class ConGroupController : IConGroupController
     {
+#pragma warning disable 649
         [Dependency] private readonly IResourceManager _resourceManager;
         [Dependency] private readonly IConfigurationManager _configurationManager;
         [Dependency] private readonly ILogManager _logManager;
         [Dependency] private readonly IPlayerManager _playerManager;
+#pragma warning restore 649
 
         private ConGroupContainer _groups;
         private SessionGroupContainer _sessions;