Add "Quit to desktop" button in pause menu (#558)

* Add "Quit to desktop" button in pause menu

* classes & custom_weapons: fix for SP

* "Quit to desktop" button for MP

data/cdata/ui_scripts/patches/__init__.lua

@@ -1,5 +1,6 @@
 require("language")
 require("background_effects")
+require("pausequit")
 
 if game:issingleplayer() then
     require("sp_unlockall")

data/cdata/ui_scripts/patches/pausequit.lua

@@ -0,0 +1,32 @@
+if (Engine.InFrontend()) then
+    return
+end
+
+if game:issingleplayer() and Engine.GetDvarString("mapname") == "coup" then
+    LUI.onmenuopen("sp_pause_menu", function(element)
+        local menu = element:getFirstChild()
+        menu:AddButton("@MENU_SP_SKIP_MISSION", function()
+            Engine.Exec("map blackout")
+        end)
+    end)
+end
+
+if game:issingleplayer() then
+    LUI.onmenuopen("sp_pause_menu", function(element)
+        local menu = element:getFirstChild()
+        menu:AddButton("@MENU_QUIT_TO_DESKTOP", function()
+            LUI.FlowManager.RequestAddMenu(nil, "quit_popmenu")
+        end)
+    end)
+end
+
+if not game:issingleplayer() then
+    local quitToDesktop = function()
+        LUI.FlowManager.RequestAddMenu(nil, "quit_popmenu")
+    end
+    local addQuitButton = function(element)
+        local menu = element
+        menu:AddButton("@MENU_QUIT_TO_DESKTOP", quitToDesktop)
+    end
+    LUI.onmenuopen("mp_pause_menu", addQuitButton)
+end