score: Merge address API into one file
score: Merge wkspace API into one file
score: Include missing <rtems/score/address.h>
score: PR1782: CPU_USE_DEFERRED_FP_SWITCH

Do not redefine CPU_USE_DEFERRED_FP_SWITCH.
score: Include missing <rtems/score/thread.h>
score: Create heap implementation header

Move implementation specific parts of heap.h and heap.inl into new
header file heapimpl.h.  The heap.h contains now only the application
visible API.
posix: Include missing <stdint.h>
score: Create stack implementation header

Move implementation specific parts of stack.h and stack.inl into new
header file stackimpl.h.  The stack.h contains now only the application
visible API.