normalize modelines/headers across src/*.c

src/render.c

@@ -1,7 +1,13 @@
 /*
  * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ * render.c: Renders (determines position/sizes) the layout tree, updating the
+ *           various rects. Needs to be pushed to X11 (see x.c) to be visible.
+ *
  */
-
 #include "all.h"
 
 /* change this to 'true' if you want to have additional borders around every