fixes and improvements on the faraday adapter
- implement `Faraday::Adapter#build_connection´ (adapter seems to expect it)
- implement
Faraday::Adapter#close(adapter seems to expect it) - use
Faraday::Adapter#request_timeoutto translate faraday timeouts to httpx timeouts; - ensure that the same HTTPX sesion object gets reused
In the process, also had to tweak the parallel manager, by reimplementing the faraday APIs I was required to implement in the first place, in order to obe able to reuse something (which just shows that this faraday parallel API was poorly thought out).
Closes #242 (closed)