Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibCore/CElapsedTimer.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <sys/time.h>
+
+class CElapsedTimer {
+public:
+    CElapsedTimer() {}
+
+    bool is_valid() const { return m_valid; }
+    void start();
+    int elapsed() const;
+
+private:
+    bool m_valid { false };
+    struct timeval m_start_time {
+        0, 0
+    };
+};