Version 4.2.1
Merge branch 'master' of https://github.com/BuildCraft/BuildCraft
ACT needs to support recipes with variable outputs

For example, ChristmasCraft Gifts that use input item NBT to determine
the output item.
Add a null check in dropItems()
Improve perf of ACT by caching OreDict info
Remove any possibility for CCMEs in Item pipes

Fixes
http://forum.feed-the-beast.com/threads/direwolf-20-1-6-4-public-beta.35476/page-18#post-500244

I should note that I still can't see how that could have happened, this
commit just made it utterly impossible.
Merge nightly into marmot
Slow Item Pipe max speed so the code can keep up