This changes the context implementations to perform a lazy initialization
of their respective contexts. This potentially leads to less resource usage.

…ead api

With lazy creation of stacks, the staged queue is no longer needed since
tsks can be created immediately and scheduled when they are ready.

All executrs and calls to register_thread_nullary/etc need to are
modified to remove the run_now param since it is no longer meaningful.

…scheduler

Add new type thread_schedule_hint to replace direct use of core number
in any task creation or scheduler functions.

Starting work on new guided pool example.

…h numa hints

…ting a future

Remove debug messages and cleanup async/then _execute functions

…ypos

Clean up debug messages etc in guided executor

…ation

If ABP Scheduler is disabled, then the abp fifo/lifo definitions
are not available and compilation fails.
Add definitions here protected by an #ifdef so that are visible when
needed.

…ywhere"

This reverts commit ea5321e.

…ead api

With lazy creation of stacks, the staged queue is no longer needed since
tsks can be created immediately and scheduled when they are ready.

All executrs and calls to register_thread_nullary/etc need to are
modified to remove the run_now param since it is no longer meaningful.

… cleanup

Remove some commented out performance counter code,
it can be replaced if ever needed