Feature - #352 rc file should support includes

- Added include file support to Config.cpp.
- Implemented isAbsolutePath helper.
- Added unit tests for isAbsolutePath.
- Fixed small bug in bug.bulk.t.
- Added TODO items to config.t.cpp.

src/Config.h

@@ -40,7 +40,7 @@ public:
   Config (const Config&);
   Config& operator= (const Config&);
 
-  bool load (const std::string&);
+  bool load (const std::string&, int nest = 1);
   void createDefaultRC (const std::string&, const std::string&);
   void createDefaultData (const std::string&);
   void setDefaults ();