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().
