re-add the emacs and vim modelines to all source files

this makes things easier and IMHO these two lines do not cause any
disturbance.

examples/co2injection_immiscible_vcfv.cpp

@@ -1,3 +1,5 @@
+// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// vi: set et ts=4 sw=4 sts=4:
 /*
   Copyright (C) 2012-2013 by Andreas Lauser