3.2:Spawn things from `Things`

[YeOldeDM]

Find a position on your map to count as the player start. Will be generated later.
Map gets func spawn( category, thing, cell ) to spawn in thing from Things singleton at cell cell.
Delete the instance of Player from your Map.
Call this func on _ready() to bring in the player programmatically. Do the same to spawn some of your Props.