amplified JaneStreet tests

We came up with a few additions to js-args expressing two general ideas:

1.  Independent of nesting level, function calls ending in "(fun _ ->" should assume that no additional arguments will be passed and indent just 2 chars in from the prior indentation.  (The examples are much clearer than that statement.)

2.  Lines beginning with binary operators should align with their left arguments, incl. &&, <=, etc.  This affects the indentation of "if" conditions and parenthesized expressions.  (Again, I think the examples probably say this better.)

(1) is extremely JaneStreet-specific.  (2) might be of more general interest.