Fix bug in main.arguments

Process.arguments is never empty as the first item is always the path of the script.
Except for in a playground where it actually is empty.

SwiftShell/Context.swift

@@ -52,7 +52,8 @@ public final class MainShellContext: ShellContextType {
 		}
 	}
 
-	public lazy var arguments: [String] = Process.arguments.isEmpty ? [] : Array(Process.arguments.dropFirst())
+
+	public lazy var arguments: [String] = Process.arguments.count <= 1 ? [] : Array(Process.arguments.dropFirst())
 	public lazy var name: String = Process.arguments.first.map(NSURL.init)?.lastPathComponent ?? ""
 
 	private init() {