SL-14906 More adjustments to guidebook

The Guidebook should remember it's open/closed state between sessions.
The Guidebook button should show as pressed while the Guidebook is open.

indra/newview/app_settings/commands.xml

@@ -88,8 +88,10 @@
            icon="Command_HowTo_Icon"
            label_ref="Command_HowTo_Label"
            tooltip_ref="Command_HowTo_Tooltip"
-           execute_function="Help.ToggleHowTo"
-           is_running_function="Help.HowToVisible"
+           execute_function="Floater.ToggleOrBringToFront"
+           execute_parameters="how_to"
+           is_running_function="Floater.IsOpen"
+           is_running_parameters="how_to"
            />
   <command name="inventory"
            available_in_toybox="true"

indra/newview/llviewermenu.cpp

@@ -5000,13 +5000,6 @@ bool tools_visible_take_object()
 	return !is_selection_buy_not_take();
 }
 
-bool enable_how_to_visible(const LLSD& param)
-{
-	LLFloaterWebContent::Params p;
-	p.target = "__help_how_to";
-	return LLFloaterReg::instanceVisible("how_to", p);
-}
-
 class LLToolsEnableBuyOrTake : public view_listener_t
 {
 	bool handleEvent(const LLSD& userdata)
@@ -9103,7 +9096,6 @@ void initialize_menus()
 	// Help menu
 	// most items use the ShowFloater method
 	view_listener_t::addMenu(new LLToggleHowTo(), "Help.ToggleHowTo");
-	enable.add("Help.HowToVisible", boost::bind(&enable_how_to_visible, _2));
 
 	// Advanced menu
 	view_listener_t::addMenu(new LLAdvancedToggleConsole(), "Advanced.ToggleConsole");

indra/newview/skins/default/xui/en/floater_how_to.xml

@@ -10,6 +10,7 @@
   min_width="335"
   name="floater_how_to"
   single_instance="true"
+  save_visibility="true"
   save_rect="true"
   title="WELCOME ISLAND GUIDEBOOK"
   width="780"