replace char* by const char*, to avoid warnings by g++-4.2

[[Imported from SVN: r5084]]

common/configparser.cc

@@ -190,7 +190,7 @@ string ConfigParser::get(const string& key, const string& defaultValue)
     return defaultValue;
 }
 
-string ConfigParser::get(const string& key, char* defaultValue)
+string ConfigParser::get(const string& key, const char* defaultValue)
 {
   if (hasKey(key))
     return (*this)[key];

common/configparser.hh

@@ -157,7 +157,7 @@ namespace Dune {
      * \param defaultValue default if key does not exist
      * \return value as string
      */
-    std::string get(const std::string& key, char* defaultValue);
+    std::string get(const std::string& key, const char* defaultValue);
 
 
     /** \brief get value as int