Revert "macroprocessor: interpret arrays passed on the command line as arrays...

Revert "macroprocessor: interpret arrays passed on the command line as arrays instead of strings. closes #1578"

Commit 204d9cd0 fails with gcc 4.9 (I checked that it works flawlessly
with 6.x). The error message is:

MacroDriver.cc:63:24: error: 'class std::basic_string<char>' has no member named 'front'
         if (it->second.front() == '[' && it->second.back() == ']')
                        ^
MacroDriver.cc:63:53: error: 'class std::basic_string<char>' has no member named 'back'
         if (it->second.front() == '[' && it->second.back() == ']')

Ideally we should bump the version of gcc used in the build system, but I will not do that before the
next bug fix release. I suppose it is easier to replace the front() and back() methods.

(cherry picked from commit 4d89452e)

preprocessor/macro/MacroDriver.cc

 /*
- * Copyright (C) 2008-2018 Dynare Team
+ * Copyright (C) 2008-2017 Dynare Team
  *
  * This file is part of Dynare.
  *
@@ -64,11 +64,7 @@ MacroDriver::parse(const string &f, ostream &out, bool debug, bool no_line_macro
       }
     catch (boost::bad_lexical_cast &)
       {
-        if (it->second.front() == '[' && it->second.back() == ']')
-          // If the input is an array. Issue #1578
-          file_with_endl << "@#define " << it->first << " = " << it->second << endl;
-        else
-          file_with_endl << "@#define " << it->first << " = \"" << it->second << "\"" << endl;
+        file_with_endl << "@#define " << it->first << " = \"" << it->second << "\"" << endl;
       }
   file_with_endl << in.rdbuf() << endl;