fix #2760

[jonsequitur]

This addresses #2760 by adding a new property currently named Argument.CaptureRemainingTokens.

I'm not sure this is the right name but the behavior is that this argument will capture everything following it regardless of whether it happens to match some well-known symbol. A few notes on this implementation:

• It's intended to be used with enumerable types but this is not enforced.
• It stops capturing when it reaches the arity limit for the argument. For this reason, a name like Greedy might be more accurate. Can we assume this term is intuitive enough?
• The -- token has no special meaning when captured by an Argument with this property set to true. It gets captured as one of the tokens.

@baronfel @tmds Thoughts?

[KalleOlaviNiemitalo]

The -- token has no special meaning when captured by an Argument with this property set to true. It gets captured as one of the tokens.

That is what I would expect.

[KalleOlaviNiemitalo]

It's intended to be used with enumerable types but this is not enforced.

I imagine a custom parser could very well transform this token sequence to a non-enumerable type.