Support args for ParserProtocol.setNextRule

[introom]

Currently, we can only do setNextRule("ruleName"). But sometimes, the nextRule may in the form of ：
ruleName :arg1 :arg2 = expr

As the argument is set by the caller, so, the currentRule needn't be in the form of term based Action(arg). It should directly be the data.
To accomplish this, I used the codeName to tell this apart. (I don't know if it's a good way to go or not.) When the codeName is None, it means the arg is already the pure data, which needn't be self._eval again.
A sample link:
https://github.com/introom/parsley/blob/master/ometa/interp.py#L154

To support rule invocation with argument, of course some other parts should be modified too.
I will discuss it later when this issue gets its attention.

@washort @habnabit

[introom]

I currently make the currentRule support two form:

1. "ruleName" #rule without args
2. ("ruleName", (args, args)) rule with args.
   See
   https://github.com/twisted/parsley-protocols/blob/smtp/parseproto/util/tube.py#L30

[habnabit]

Your code is a little behind; setNextRule was removed. You could check if receiver.currentRule is a tuple, though.