Choose color more adapted to both white and black background

 + Would look better on both White and Dark background, since White is not
 displayed on White background and Yellowi (and Red) were too flashy.

src/licencing.ml

@@ -1219,6 +1219,7 @@ let print ~cecill =
          ))
   in
 
+  Messages.debug "First ask";
   Messages.info "Choose your language 'Fr' or 'En': ";
 
   let ( warn, licence ) =

src/messages.ml

@@ -57,8 +57,11 @@ let log_already () =
 type color =
   | Green
   | Red
+  | Dark_red
   | Yellow
+  | Amber
   | White
+  | Gray
   | Plum
   | Cyan
 ;;
@@ -83,8 +86,11 @@ let print ~color ~style message =
       (function
         | Green -> cpcolor ~color:`Green message
         | Red -> cpcolor ~color:`Red message
+        | Dark_red -> cpcolor ~color:`Dark_red message
         | Yellow -> cpcolor ~color:`Yellow message
+        | Amber -> cpcolor ~color:`Amber message
         | White -> cpcolor ~color:`White message
+        | Gray -> cpcolor ~color:`Gray message
         | Plum -> cpcolor ~color:`Plum message
         | Cyan -> cpcolor ~color:`Cyan message
       ) |> (* Finaly print escaped string *)
@@ -128,14 +134,14 @@ let debug message =
 let info message =
   check_verbosity ~debug ~f:(fun () ->
          let mess = message ^ "\n" in
-         print ~color:White ~style:Bold mess
+         print ~color:Gray ~style:Bold mess
        ) 3
 ;;
 
 let warning message =
   check_verbosity ~debug ~f:(fun () ->
          let mess = message ^ "\n" in
-         print ~color:Red ~style:Bold mess
+         print ~color:Dark_red ~style:Bold mess
        ) 1
 ;;
 
@@ -184,7 +190,7 @@ let ok message =
 let tips message =
   check_verbosity ~debug ~f:(fun () ->
          let mess = message ^ "\n" in
-         print ~color:Yellow ~style:Normal mess
+         print ~color:Amber ~style:Normal mess
        ) 4
 ;;