Remove unused usings from formatter.cs

Author: Kapil Borle

Engine/Formatter.cs

@@ -1,10 +1,5 @@
-using System;
 using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
 using System.Management.Automation;
-using System.Management.Automation.Runspaces;
-using Microsoft.Windows.PowerShell.ScriptAnalyzer.Generic;
 
 namespace Microsoft.Windows.PowerShell.ScriptAnalyzer
 {