Adding new units for the RGB and HSV values in the Navigator tool (below

Histogram). Click on one of thes two columns to cycle to a new unit
independantly, between [0-1], [0-255], [%]  (Hue stays in degree instead
of percent). The current unit is saved in Options for new Editor tabs or
between sessions.

rtgui/options.h

@@ -86,6 +86,13 @@ private:
                     const Glib::ustring& entryName, Glib::ustring& destination);
 
 public:
+
+    enum class NavigatorUnit {
+        NU_PERCENT,
+        NU_0_255,
+        NU_0_1,
+        NU__COUNT,
+    };
     bool savesParamsAtExit;
     SaveFormat saveFormat, saveFormatBatch;
     Glib::ustring savePathTemplate;
@@ -133,6 +140,8 @@ public:
     bool fbShowExpComp;
     bool fbShowHidden;
     int  fbArrangement;
+    NavigatorUnit navRGBUnit;
+    NavigatorUnit navHSVUnit;
     bool multiUser;
     static Glib::ustring rtdir;
     Glib::ustring version;