Better scenario listing options

[Wuzzy]

In the options, you can change the way the scenario list is sorted. You can choose to sort by difficulty.

But locked scenarios should stay locked if you just change the sorting method. Currently, sorting by difficulty automatically unlocks everything (which is a cheat, actually).

Because in this sorting, it would be not too terribly clear which missions to play in order to unlock a new one and the hover text would be misleading, I suggest to change the hover text when hovering a locked mission: Instead of just saying that “previous” scenarios have to be won, be more specific. Write something like “Finish 4 more scenarios of Wacky Worlds to unlock this scenario.”.

The disabling of locked missions should be considered a cheat (https://openrct2.org/forums/topic/1439-features-that-should-be-considered-cheats/) and moved somewhere else.