* eval.h, eval.c, debug.h, debug.c (scm_evaluator_traps): Moved

* eval.h, eval.c, debug.h, debug.c (scm_evaluator_traps): Moved
from debug.c --> eval.c

* eval.h, eval.c (scm_eval_options_interface): New options
interface.
(SCM_EVAL_STACK): New option: Size of newly created stacks,
i.e. stacks for new threads.

* eval.c (unsafe_setjmp): Removed with #if 0.

* eval.c, numbers.c, unif.c, srcprop.c: Added a few curly braces
to avoid compiler warnings.