Expressions - Refactor

- The A3::Arg object is very similar to the E9::Term object, so the two are
  being merged.  First step is to separate A3::Arg into it's own space, then
  add a _type member.
- Added more valid stop characters as terminators for various arg types.
- Removed redundant E9 special handling for dates, which is already built in
  to the Date object.

src/Arg.h

@@ -0,0 +1,54 @@
+////////////////////////////////////////////////////////////////////////////////
+// taskwarrior - a command line task list manager.
+//
+// Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
+// All rights reserved.
+//
+// This program 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 2 of the License, or (at your option) any later
+// version.
+//
+// This program 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
+// this program; if not, write to the
+//
+//     Free Software Foundation, Inc.,
+//     51 Franklin Street, Fifth Floor,
+//     Boston, MA
+//     02110-1301
+//     USA
+//
+////////////////////////////////////////////////////////////////////////////////
+#ifndef INCLUDED_ARG
+#define INCLUDED_ARG
+#define L10N                                           // Localization complete.
+
+#include <string>
+
+#define ARGUMENTS_SEQUENCE_MAX_RANGE 1000
+
+class Arg
+{
+public:
+  Arg ();
+  Arg (const std::string&);
+  Arg (const std::string&, const std::string&);
+  Arg (const std::string&, const std::string&, const std::string&);
+  Arg (const Arg&);
+  Arg& operator= (const Arg&);
+  bool operator== (const Arg&) const;
+
+  
+public:
+  std::string _raw;      // Raw input token, never modified
+  std::string _type;     // Data type
+  std::string _category; // Categorized argument
+};
+
+#endif
+////////////////////////////////////////////////////////////////////////////////