Add a new Saltpetre recipe because industrial amounts are unpleasant to make

[ohjoy]

Personally wouldn't mind saltpetre being easier to make, although black powder bombs are probably the main issue with the people that are against it, I would guess.

I'll break Black Powder down and hopefully somebody more experienced in killing can give us a threat analysis:

• Charcoal: Easy to obtain. Grab some paper, a lighter, and a salt shaker from the cafeteria.
  
• Sulfur: Requires a chem dispenser.
  
• Potash: Easy to obtain. Grab some paper, a lighter, and some water.
  
• Urine: Easy to obtain, but slow.
  
• Compost: Requires compost tank.
  

In summation, Saltpetre is slow and requires a compost tank to obtain, unless they have a Saltpetre bottle. So Black Powder requires a compost tank and a chem dispenser and is slow to make unless they have a Saltpetre bottle.

My suggestion of Nitrogen replacing Urine gives Saltpetre two additional methods of being made:

• Chem dispenser.
  
• Bean plants.
  

This means Saltpetre can be:

• Slow
  
• Fast (Chem dispenser)
  
• Reasonably fast (Bean plants)
  

But still requires a compost tank.
So Black Powder would require a compost tank and a chem dispenser, and would not be slow since a chem dispenser is present anyways. 

I think the main concern is: would letting Urine be substituted for Nitrogen make it too easy for antagonists to obtain Black Powder in comparison to the other explosive chems? I think we need some experienced antagonist players to weigh in on this, but my suspicion is that it would be too easy, which is very unfortunate.

If there is really no other way to time-gate Black Powder, then so be it. Maybe setting the Saltpetre reaction at a certain temperature, or making it release a toxic cloud like Cyanide, or making it blow up a little on mixing, but I don't know if any of that would even do much at all.