Fixed: AttributeError when quitting from menu
Submodule pymclevel updated.

Submodule pymclevel:
    > 5865930 - Correct lighting values for many blocks. Add Locked Chest.
    > c4da23d - Add Vector.intfloor
    > e0d999c - Add Vector.normalize
    > b511bb6 - Add method Vector.length
    > 86640ec - Fixed: Remove self from TAG_Compound's key not found error message
    > e8364f8 - Added: Division and scalar multiplication to Vector
    > 6ed8c45 - Fixed: TileEntity.copyWithOffset adjusts mob position data for mob spawner blocks