Moving corlib files out of "System" directory into root

BeefLibs/corlib/src/IO/FileMode.bf

@@ -0,0 +1,32 @@
+// This file contains portions of code released by Microsoft under the MIT license as part
+// of an open-sourcing initiative in 2014 of the C# core libraries.
+// The original source was submitted to https://github.com/Microsoft/referencesource
+
+using System;
+
+namespace System.IO
+{
+	public enum FileMode
+	{
+        /// Creates a new file. Fails if the file already exists.
+		CreateNew = 1,
+    
+        /// Creates a new file. If the file already exists, it is overwritten.
+		Create = 2,
+    
+        /// Opens an existing file. Fails if the file does not exist.
+		Open = 3,
+    
+        // Opens the file if it exists. Otherwise, creates a new file.
+		OpenOrCreate = 4,
+    
+        // Opens an existing file. Once opened, the file is truncated so that its
+        // size is zero bytes. The calling process must open the file with at least
+        // WRITE access. Fails if the file does not exist.
+		Truncate = 5,
+        
+        // Opens the file if it exists and seeks to the end.  Otherwise, 
+        // creates a new file.
+		Append = 6,
+	}
+}