Added
* Added the option to pass arguments into the long running task of a background worker.
* Added the option to manually control when the background worker task is set to **Done**.
* Added dispose function to control resource deallocation in a background worker.
Changed
* Set background threads in the background worker as daemon threads to prevent blocking the main thread.
* Changed base class of `Message` from `UserDict` to `object` because in IronPython 2.7 `UserDict` is an old-style class. The behavior of dictionary-like is still preserved.
Removed