Add r_listmodes, change one comment and a message

r_listmodes does the same as vid_listmodes, but is more consistent with
r_mode

the rest is cosmetical

src/client/sound/ogg.c

@@ -17,7 +17,7 @@
  *
  * =======================================================================
  *
- * This file implements an interface to libvorbis for decoding
+ * This file implements an interface to stb_vorbis.c for decoding
  * OGG/Vorbis files. Strongly spoken this file isn't part of the sound
  * system but part of the main client. It justs converts Vorbis streams
  * into normal, raw Wave stream which are injected into the backends as

src/client/vid/glimp_sdl.c

@@ -171,7 +171,7 @@ CreateSDLWindow(int flags, int w, int h)
 				SDL_DestroyWindow(window);
 				window = NULL;
 
-				Com_Printf("Can't get display mode: %s\n", SDL_GetError());
+				Com_Printf("Still in wrong display mode: %ix%i instead of %ix%i\n", real_mode.w, real_mode.h, w, h);
 
 				return false;
 			}

src/client/vid/vid.c

@@ -543,6 +543,7 @@ VID_Init(void)
 	// Commands
 	Cmd_AddCommand("vid_restart", VID_Restart_f);
 	Cmd_AddCommand("vid_listmodes", VID_ListModes_f);
+	Cmd_AddCommand("r_listmodes", VID_ListModes_f); // more consistent with r_mode
 
 	// Initializes the video backend. This is NOT the renderer
 	// itself, just the client side support stuff!