NM database file format:
------------------------
char[4] magic = "NMDB"
u8 version = 1
repeat {
	s16 x
	s16 z
	s16 y
	u16 player id
}

* everything little endian
* s16's are serialized like this:
* 	write_u16(value + 32768)
* the player id corresponds to the player listed on that line in nm_players.db (counting from 0)