New routines for reading binary eclipse format files

1) Start of new class EclFile which includes one anonomus namespace with routines for reading binary eclipse format files
  2) One very basic test of EclFile constructor included in test_EclFile.cpp
      - testing that file exist, throwing an exception if not.

tests/test_EclFile.cpp

@@ -0,0 +1,42 @@
+/*
+   +   Copyright 2019 Equinor ASA.
+   +
+   +   This file is part of the Open Porous Media project (OPM).
+   +
+   +   OPM is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
+   +   the Free Software Foundation, either version 3 of the License, or
+   +   (at your option) any later version.
+   +
+   +   OPM is distributed in the hope that it will be useful,
+   +   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   +   GNU General Public License for more details.
+   +
+   +   You should have received a copy of the GNU General Public License
+   +   along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+   +   */
+
+
+#include "config.h"
+#include <iostream>
+#include <stdio.h>
+#include <iomanip>    
+#include <math.h>  
+#include <algorithm>
+
+#include <examples/test_util/EclFile.hpp>
+
+#define BOOST_TEST_MODULE Test EclFile
+#include <boost/test/unit_test.hpp>
+
+
+
+BOOST_AUTO_TEST_CASE(TestConstructor){
+
+    EclFile file1("../../tests/NORNE_ATW2013.INIT");
+    
+    BOOST_CHECK_THROW(EclFile file1("../../../../tests/XXXXX_ATW2013.INIT"), std::runtime_error );
+
+}
+
+