* Replace `/bin/sleep` with just `sleep`, i.e. use environment variable
`$PATH` to locate binary.
* Replace `/usr/share/zoneinfo` with `$TZDIR` when it is defined,
fallback to hardcoded path otherwise. This is the same behavior that
Glibc2 normally have, see man 3 tzset.
* Merge upcoming async with current.
* Various improvements to selectors (mostly docs).
Two changes to highlight:
* Renamed ``setEvent`` to ``trigger``
* Reused setBlocking from nativesockets.
* Various changes/fixes to asyncdispatch after upcoming merge.
* Make some attempts to be compatible with older selectors.
* Reuse epoll module in ioselectors_epoll.
* Fix kqueue.nim and ansi_c.nim to support dragonfly.
* Fix ioselectors.nim, threads.nim to support dragonfly.
* Fix deprecated dealloc call in tioselectors.nim.
* Fix tfsmonitor.nim test to run only on Linux.
* Fix osproc.nim return wrong exit codes.
* Fix getAppFilename() for dragonfly.
* Fix proper exit code handling.
* Fix#5128, #5184.
Removed flush() procedure from ioselectors.nim
Changed methods of work with application-driven data
* Make cache switch for kqueue, update test for it.
* Fix registerProcess bug returns wrong id.
Fix tupcoming_async test to compile with upcoming again.
Change socket() as unique identifier to dup(socket) as unique identifier.
