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/LibHTML/Dump.h

@@ -0,0 +1,13 @@
+#pragma once
+
+class Node;
+class LayoutNode;
+class StyleRule;
+class StyleSheet;
+class StyledNode;
+
+void dump_tree(const Node&);
+void dump_tree(const StyledNode&);
+void dump_tree(const LayoutNode&);
+void dump_sheet(const StyleSheet&);
+void dump_rule(const StyleRule&);