Add being able to disable unfocus pause

It's sometimes unwanted by people, and it's unwanted enough that there
exist instructions to hexedit the binary to remove it (
https://distractionware.com/forum/index.php?topic=3247.0 ).

Fun fact, the unfocus pause didn't exist in 2.0.

desktop_version/src/Input.cpp

@@ -527,16 +527,21 @@ void menuactionpress()
             }
             break;
         case 5:
+            // toggle unfocus pause
+            game.disablepause = !game.disablepause;
+            music.playef(11);
+            break;
+        case 6:
             // toggle fake load screen
             game.skipfakeload = !game.skipfakeload;
             music.playef(11);
             break;
-        case 6:
+        case 7:
             // toggle translucent roomname BG
             graphics.translucentroomname = !graphics.translucentroomname;
             music.playef(11);
             break;
-        case 7:
+        case 8:
             //back
             music.playef(11);
             game.returnmenu();