Cleanup & Fixes for .NET 5 (#309)

- [X] Fixes several bugs
- [X] Updates more ordinal issues
- [X] Cleans up the code a bit
- [X] Turns classes static that should have been
- [X] Changes TcpServer.Instances to a HashSet

Bumps release version

Projects/UOContent/Gumps/Props/SetBodyGump.cs

@@ -310,7 +310,7 @@ namespace Server.Gumps
 
                 for (var i = 0; i < m_GroupNames.Length; ++i)
                 {
-                    if (DisplayName.StartsWith(m_GroupNames[i]))
+                    if (DisplayName.StartsWith(m_GroupNames[i], StringComparison.Ordinal))
                     {
                         DisplayName = DisplayName.Substring(m_GroupNames[i].Length);
                         break;