Add "English sprites" setting

It'll start working in the next commit... See the description there.

(This commit does not add the new strings to the language files, since
Terry now added them separately in his own branch)

desktop_version/src/Input.cpp

@@ -797,6 +797,16 @@ static void menuactionpress(void)
             game.savestatsandsettings_menu();
             music.playef(Sound_VIRIDIAN);
             break;
+        case 5:
+            // english sprites
+            loc::english_sprites = !loc::english_sprites;
+            if (!loc::english_sprites)
+            {
+                graphics.grphx.init_translations();
+            }
+            game.savestatsandsettings_menu();
+            music.playef(Sound_VIRIDIAN);
+            break;
         default:
             //back
             music.playef(Sound_VIRIDIAN);