Move animated gif images to the test/images folder

... to make them accessible to the help_dialog test if built with CMake.

examples/animgifimage-simple.cxx

@@ -24,7 +24,7 @@ int main(int argc, char *argv[]) {
   // of the `canvas` widget and start it immediately.
   // We use the `DONT_RESIZE_CANVAS` flag here to tell the
   // animation *not* to change the canvas size (which is the default).
-  const char *default_image = "../test/pixmaps/fltk_animated.gif";
+  const char *default_image = "../test/images/fltk_animated.gif";
   Fl_Anim_GIF_Image animgif(/*name_=*/ argv[1] ? argv[1] : default_image,
                           /*canvas_=*/ &canvas,
                            /*flags_=*/ Fl_Anim_GIF_Image::DONT_RESIZE_CANVAS);

test/help_dialog.html

@@ -264,7 +264,7 @@ Nested OL/UL:
     <TD><IMG SRC="images/tiny.png" alt="Tiny FLTK logo"></TD>
     <TD>Tiny FLTK logo.</TD>
   </TR><TR>
-    <TD><IMG SRC="pixmaps/fltk_animated.gif" WIDTH="200" HEIGHT="50" alt="Animated FLTK logo"></TD>
+    <TD><IMG SRC="images/fltk_animated.gif" WIDTH="200" HEIGHT="50" alt="Animated FLTK logo"></TD>
     <TD>Animated FLTK logo.</TD>
   </TR><TR>
     <TD><IMG SRC="images/Fl_Value_Input.png" alt="Fl_Value_Input"></TD>