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

doc/man/taskrc.5

@@ -230,6 +230,18 @@ Colors any task assigned to project X.
 .TP
 .B color.keyword.X=on_blue
 Colors any task where the description contains X.
+
+.TP
+.B color.header=green
+Colors any of the messages printed prior to the report output.
+
+.TP
+.B color.message=green
+Colors any of the messages printed after the report output.
+
+.TP
+.B color.footnote=green
+Colors any of the messages printed last.
 .RE
 
 .TP