Trivial formatting fixes to all examples, simple functional fixes to

* docs/tutorial/gtk-tut.sgml, docs/examples/*: Trivial formatting
	fixes to all examples, simple functional fixes to rangewidgets example.

examples/base/base.c

@@ -13,5 +13,5 @@ int main( int   argc,
     
     gtk_main ();
     
-    return(0);
+    return 0;
 }