[D11] frontend changes wip fix #4; PagedUI no longer automatically opens the first page in the list, probably best not to assume the ordering, and Rust pushes it manually anyway, and it makes it easier to deal with PagedUIs which don't instantly activate, which leads onto the next point - in game code no longer references the frontend (which was crashing since it is no longer loaded then), the options menu and corpse stat panel both simply create their own PagedUI instances. Not really sure why they need this at all since they are both single pages, but I guess it helps should they get more complicated. Some simplifications to PagedUI.