expand recipe butylene to fedefl butene

[fchichorro]

Ecoinvent flowable Butene gets its CFs for Butylene. According to Wikipedia, Butene and Butylene are synonyms. This commit thus maps recipe butylene to FEDEFL's Butene.

The existing mapping recipe butylene to fedefl 1-Butene is used as the template for the context mapping.

[bl-young]

I'm holding off on this one as we should not have duplicate flowables in FEDEFL. Need to confirm that 1-Butene and Butene are indeed different flows, and if so, which one is more appropriate to match to ReCiPe butylene.