I don't know if this should be commited. Related: #837
Benchmarks
- async cost: The cost of pushing work to the TaskManager
- async round-trip: A bit more realistic, wait on a task
output on my machine: release:
```
Benchmark:
async cost:
enqueueing: 377ms
work done: 378ms
total: 384ms
async round-trip:
total: 1009ms
```
debug:
```
Benchmark:
async cost:
enqueueing: 491ms
work done: 495ms
total: 519ms
async round-trip:
total: 1245ms
```
Are this tests meaningfull?
Are the constants(1us, 50000 iterations) sensible?
Interface? command-line-argument / from the gui?
What should the output be to be more understandable? Is `std::cout` ok?