…be used for async deadlines

…ynchronous deadlines and asynchronous cancellation

…ync-cancellable`

* added `isPromise`, `isPromiseLike`, `isIterable`, `isAsyncIterable` to detect async and generator interfaces
* timed decorator works for regular values, `PromiseLike` and `Iterable` and `AsyncIterable`
* introduced `ContextTimed` type and other `Context*` types
* stack trace is refers when construction time, so decorator takes error class constructor

…tors

… tasks

* Created a `Plug` class for managing the locking of scheduling and queuing loops
* Using `performance.now()` for acquiring the current time

…getGroupTasks`

…ath`, `taskGroup` is refered to as `path` now

…finite timers

…ger`

* tasks can be cancelled at any stage: scheduled, queued or active
* `TaskData` is suitable to be encoded into JSON and back
* Graceful shutdown of `TaskManager`
* `TaskHandler` gets `TaskInfo` as second parameter after the `ContextTimed`

…pendency

…uld do nothing

There are 3 properties for the `timed` wrapper:

A. If timer times out, signal is aborted
B. If signal is aborted, timer is cancelled
C. If timer is owned by the wrapper, then it must be cancelled when the
target finishes

There are 4 cases where the wrapper is used and where the properties are
applied:

  1. Nothing is inherited - A B C
  2. Signal is inherited - A B C
  3. Timer is inherited - A
  4. Both signal and timer are inherited - A*

B and C are only applied to case 1 and 2, because that's when the `Timer`
is owned by the wrapper.

*Case 4 is a special case, because the timer and signal are inherited,
so it is assumed that the handlers are already setup betwen the timer
and signal.

…factored out common functionality in contexts domain