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.
There are two main problems with flipgravity():
1. It doesn't work for an already-flipped crewmate.
2. It doesn't work on the player.
This commit addresses both of those issues.
Resizing the vector does the same thing that the loops did, it changes
the size for the vector and initializes it with default-constructed
elements (or 0 or its equivalent for POD types).
Where a specific value is needed, it is set with the second
parameter of resize().
