Adventure Mode Site Helpers: SC_NEW_MAP_AVAILABLE state change and World::GetCurrentSiteIdsWithExtraRange

[UnknowableCoder]

After doing some research on the ways to properly get access to site IDs in Adventure Mode, I realized the SC_MAP_LOADED state change only triggers on transitioning from no map to having a map loaded. The logic can easily be expanded to also consider the cases when there is a map and the map changes. For this, I propose a new state change, which I have tentatively called SC_NEW_MAP_AVAILABLE.

In the same vein, while World::GetCurrentSiteId should correctly return the current site ID (or -1 if no site), some practical use cases may benefit from being able to get all sites in a caller-provided range around the adventurer. For this reason, I propose the introduction of World::GetCurrentSiteIdsWithExtraRange, which extends the logic of the former function to take an std::vector as an in-parameter and return all applicable sites, optionally with extra range in x and y and a maximum number of sites to be return (which would be ordered by ID and not distance...).