Deprecate static opCall for structs?

[Bill Baxter]

We now have struct constructors that do basically the same thing as a
static opCall.
Non-static opCall should still be ok, for implementing functors, but I
think having static opCall is just too confusing given struct literals
/ struct constructors.

Right now
struct S;
S(1,2) ;
could be 1) a static opCall, 2) a constructor call  3) a struct literal

That seems too many things sharing the same syntax to me.

--bb