Add "Results label" option to signal and image panel menus

Author: PierreRaybaut

scripts/datalab_menus.txt

@@ -189,6 +189,7 @@ Menus for signal panel:
     Bandwidth at -3dB...
     Contrast...
     Show results...
+    Results label
     Plot results...
     Delete results
   View:
@@ -415,6 +416,7 @@ Menus for image panel:
       Blob detection (LOG)...
       Blob detection (OpenCV)...
     Show results...
+    Results label
     Plot results...
     Delete results
   View: