bilrost 0.1012

[mumbleskates]

This upgrades the bilrost library to the latest release and demonstrates one new(ly public (ish)) feature that grants a large speed-up in the log benchmark.

As discussed, this does not actually benchmark borrowed decoding, which is also implemented in 0.1012; that's cheating. I'll see if I can look into how easy it might be to generalize that across benches later on.

[djkoloski]

IIRC the benchmark formatting should be generic enough to add a borrowed benchmark without much hassle. I don't think much of the logic there is benchmark-dependent.