"fold": a replacement for "reduce"

[monarch_dodra]

I'm working on something called "fold". It is designed as nothing 
more than a replacement for "reduce", but where the seed comes 
*second* in terms of arguments. It allows this:

someLongUFCSChain().reduce(intoThis);

It might not look like this, but it is a *constant* source of 
nuisance. In particular, chains that start out like this:
someLongUFCSChain().reduce();
Need to be changed into this to add a seed:
reduce(someLongUFCSChain(), intoThis);

After a couple of tries to "swap" the arguments, it was observed 
that it simply couldn't be done wihthout silent run-time 
breakage. So that was not acceptable.

The solution: Re-introduce "reduce" under a new name: "fold".
Simple as that.

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I'm taking this naming-changing event as an opportunity to 
"cleanup" reduce too. One thing that gets on my nerves is that 
"range.reduce()" is not nothrow, because it throws an exception 
if the range is empty.

I think this is wrong. popping an empty range is an *Error*, and 
should be validated by the programmer. Because of this, it is 
currently not possible to use "reduce(range)" in nothrow context.

This however, even with a name change, it *is* change of 
behavior. Do you feel this is acceptable? Do you want this change 
at all? Or do you think an Exception is fine?