Merge pull request #371 from notoria/sleep

Added the sleep predicate

diff --cc src/prolog/lib/time.pl
index 97358a7d8cbbce9862b638a4d18bdda43fd0d218,1a5649592ed1cfe21cd5ef1d2cb17a24316e466d..b41d958a79ff4fe8b2973486a1bf427bc783d5f7
--- 1/src/prolog/lib/time.pl
--- 2/src/prolog/lib/time.pl
+++ b/src/prolog/lib/time.pl
@@@ -14,15 -14,18 +14,24 @@@
  :- use_module(library(format)).
  :- use_module(library(iso_ext)).
  
+ sleep(T) :-
+     builtins:must_be_number(T, sleep),
+     (   T < 0 ->
+         throw(domain_error(not_less_than_zero, T))
+     ;   T > 0xfffffffffffffbff ->
+         throw(domain_error(not_great_than_0xfffffffffffffbff, T))
+     ;   '$sleep'(T)
+     ).
+ 
  time(Goal) :-
          '$cpu_now'(T0),
 -        Goal,
 +        setup_call_cleanup(true,
 +                           (   Goal,
 +                               report_time(T0)
 +                           ),
 +                           report_time(T0)).
 +
 +report_time(T0) :-
          '$cpu_now'(T),
          Time is T - T0,
          (   bb_get('$first_answer', true) ->