warn about crash combos

[city41]

Certain combos of objects crash SMA4. This mostly happens on very sparse levels that only have two types of objects in them. Smaghetti should warn whenever these combos are present.

Known crashes:

• a level only has brick and an ice block in it (regular, coin or muncher)

• this setup
  

• blank ice block with muncher ice block

these crashes pretty much always go away by just adding one more object to the level, such as a coin. It has to be an object, sprites don't help here.