Investigate other mods' liquids

[narc0tiq]

Examples:

• ExtraBees adds three liquids (acid, poison, glacial water);
• Railcraft adds creosote oil;
• IC2 has coolant as a liquid;
• Forestry has crushed ice (I skipped it for the initial implementation, but should still be considered);
• Forestry also has milk, and I totally forgot about it. It's an option.

Right now (as of v0.6), I think seven liquids will do, so this is a future target.