Add restartUntil operator to Eval

[johnmcclean]

Eval will restart the execution chain until the predicate holds

Eval<T> restartUntil(Predicate<? super T> p)

E.g.

int i= 0;
Eval.always(()->++i)
    .restartUntil(n->n>500000)
    .get()

Part of #986

[johnmcclean]

Released in 10.1.1