throw exception if the file couldn't be opened

[[Imported from SVN: r2259]]

common/configparser.cc

@@ -5,8 +5,8 @@
 #include <string>
 #include <sstream>
 #include <fstream>
-#include <assert.h>
 
+#include <dune/common/exceptions.hh>
 
 using namespace Dune;
 using namespace std;
@@ -17,7 +17,9 @@ ConfigParser::ConfigParser()
 void ConfigParser::parseFile(string file)
 {
   ifstream in(file.c_str());
-  assert(in);
+
+  if (!in)
+    DUNE_THROW(IOError, "Could open configuration file " << file);
 
   string prefix;
   while(!in.eof())