Initial Setup

[elcritch]

This makes an async compatible queue, see queues.nim. Then jobs.nim builds on this with a type and macro for submitting jobs to taskpools and getting a result back via an async future. Finally tasks.nim automates the jobs wrapping and adds some type extra type checking.

Here's an example of the transformations for an "asyncTasklet":

proc addNums(a, b: float): float {.asyncTask.} =
  os.sleep(100)
  echo "adding: ", a, " + ", b
  return a + b

becomes:

proc addNumsTasklet(a, b: float): float {.nimcall.} =
  os.sleep(100)
  echo "adding: ", a, " + ", b
  return a + b

proc addNums(jobResult: JobResult[float]; a, b: float) {.nimcall.} =
  let val {.inject.} = addNumsTasklet(checkParamType(a), checkParamType(b))
  discard jobResult.queue.send((jobResult.id, val))

Calling addNums:

    let res = await jobs.submit(addNums(1.0, 2.0,))

becomes:

let (jobRes_503318661, fut_503318662) = createFuture(jobs, "addNums(1.0, 2.0)")
jobs.taskpool.spawn(addNums(jobRes_503318661, 1.0, 2.0))
fut_503318662

[elcritch]

Hey @tbekas finally got a PR up. It's fairly complete but there's a few corner cases to figure out.

The openArray seem to work, but will need to verify the GC won't free the main GC data.

[elcritch]

This will need more tests, stress testing to verify the threading. It'd be nice to do some basic benchmarking as well.

Also the API's likely need some changes. In particular the jobs newJobQueue should probably return a result type.

[tbekas]

Overall a great job 👍 This PR would use some cleanup of the commented and unused code as well as some echos.