There are three map-related vectors that need to be reset in hardreset:
`map.roomdeaths`, `map.roomdeathsfinal`, and `map.explored`. All three
of these vectors use the concatenated rows system, whereby each room is
given a room number, calculated by doing X + Y*20, and this becomes
their index in each vector.
There's a double-nested for-loop to handle resetting all of these, where
the outer for-loop iterates over the Y-axis and the inner for-loop
iterates over the X-axis, but only `map.explored` is properly reset.
That's because it's the only vector that properly indexes using X +
Y*20. The other vectors reset using X, so previously, only the first row
of `map.roomdeaths` and `map.roomdeathsfinal` got reset, corresponding
with only the first row of rooms in both Dimension VVVVVV and Outside
Dimension VVVVVV getting reset.
This commit makes sure that both get reset properly.
5b2962fde0