A simple and fast two-way async channel.
Initial benchmarks for v0.1.0:
function/call time: [1.5397 ns 1.5445 ns 1.5493 ns]
extern/call time: [1.5522 ns 1.5566 ns 1.5612 ns]
ffi/call time: [2.3279 ns 2.3406 ns 2.3521 ns]
whisk/call time: [128.41 ns 128.79 ns 129.15 ns]
flume/call time: [461.08 ns 462.58 ns 464.00 ns]
whisk/threads time: [7.2141 us 7.2827 us 7.3575 us]
flume/threads time: [7.4545 us 7.6034 us 7.7496 us]