Make oil obtainable in default random adventure

[Blue-Beaker]

Oil is important in manufacturing plastic, rubber and most electronics in factory.  But Oil doesn't generate in random adventures:

• Oil Rigs doesn't generate at all.
• Treasure Chests doesn't contain oil barrels.
• Armor oils does generate, but can't be broken down for oil.

This makes any parts requiring oil unobtainable in default random adventure.
For balance, I suggest making oil barrels spawn commonly, but oil rigs spawns rarely in place of random factory in mines.

[griffi-gh]

I think the adventure mode needs a major overhaul.
but I guess just adding oil/oild rigs to worldgen wouldn't hurt.