Enhancement - header, footer, message

- Added header, footer and message sinks.
- Added individual colorization of headers, footers and messages.
- Added new configuration variables to Config.cpp, taskrc.5.
- Added colorization functions to rules.cpp

src/main.h

@@ -102,6 +102,9 @@ std::string handleCustomReport (const std::string&);
 // rules.cpp
 void initializeColorRules ();
 void autoColorize (Task&, Text::color&, Text::color&);
+std::string colorizeHeader (const std::string&);
+std::string colorizeMessage (const std::string&);
+std::string colorizeFootnote (const std::string&);
 
 // import.cpp
 std::string handleImport ();