score: Remove scheduler parameter from most ops

Remove the scheduler parameter from most high level scheduler operations
like
  - _Scheduler_Block(),
  - _Scheduler_Unblock(),
  - _Scheduler_Change_priority(),
  - _Scheduler_Update_priority(),
  - _Scheduler_Release_job(), and
  - _Scheduler_Yield().

This simplifies the scheduler operations usage.
score: Collect scheduler related fields in TCB

Add Thread_Scheduler_control to collect scheduler related fields of the
TCB.
score: Use chain nodes for ready queue support

This reduces the API to the minimum data structures to maximize the
re-usability.
score: Decouple thread and scheduler nodes on SMP

Add a chain node to the scheduler node to decouple the thread and
scheduler nodes.  It is now possible to enqueue a thread in a thread
wait queue and use its scheduler node at the same for other threads,
e.g. a resouce owner.
score: Fix thread deletion on SMP

Close the thread object in _Thread_Make_zombie() so that all blocking
operations that use _Thread_Get() in the corresponding release directive
can find a terminating thread and can complete the operation.