prefer nanosleep for sleep loadable builtin; changes for overflow in indexed array indices; make sure dynamic loading and unloading builtins updates programmable completion; document that assignment to PATH clears the command hash table; fix small memory leak from readline filename rewrite hook

tests/array.tests

@@ -125,6 +125,8 @@ echo ${c[-4]}
 d[7]=(abdedfegeee)
 
 d=([]=abcde [1]="test test" [*]=last [-65]=negative )
+d=([0]=abcde [1]="test test" [*]=last )
+d=([1]="test test" [-65]=negative )
 
 unset d[12]
 unset e[*]