Touchup-fix for Issue 1549: Keyboard camera panning only works in 3 directions using WASD keys.

I didn't like the way Advanced menu flickered, so I provided a setting to prevent the toggle that way altogether.

Adds LiruUseAdvancedMenuShortcut

indra/newview/app_settings/settings.xml

@@ -1021,6 +1021,17 @@ Found in Advanced->Rendering->Info Displays</string>
       <key>Value</key>
       <integer>0</integer>
     </map>
+    <key>LiruUseAdvancedMenuShortcut</key>
+    <map>
+      <key>Comment</key>
+      <string>Use ctrl-alt(-shift)-d to toggle the advanced menu.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <boolean>1</boolean>
+    </map>
     <key>LiruUseContextMenus</key>
     <map>
       <key>Comment</key>

indra/newview/llviewerwindow.cpp

@@ -2706,7 +2706,8 @@ BOOL LLViewerWindow::handleKey(KEY key, MASK mask)
 		(MASK_CONTROL & mask) &&
 		('D' == key || 'd' == key))
 	{
-		toggle_debug_menus(NULL);
+		if (gSavedSettings.getBOOL("LiruUseAdvancedMenuShortcut"))
+			toggle_debug_menus(NULL);
 	}
 
 	// handle shift-escape key (reset camera view)