Vacuum module rework
- Now reliably vacuums items below it
- Items can be vacuumed from the other side of a wall
- Item motion is generally somewhat smoother now
item router: make playParticles() public (VacuumModule needs it)
Removed bad equals() and hashCode() methods from BaseSTBItem
They broke item router modules for a start.
Item router now stores modules internally as a list, not a map
Map doesn't make good sense since it's hard to get good performant hashCode() and equals() methods for (non-block) STB items.
Also, sender modules can now send items through fences.