[nem-en] Debugging macros again

[vc]

> AST of expansion can be seen only in VS and only if code succeeds with
> compilation. I don't think that showing AST of code, which triggered
> error is a good default, though it is a nice idea 

Good, good. :)

It's really best way.

We must generate code by AST if:
1. Compile-time error detected and Location say "it code generated by
macro".
2. For debugging purpose. In it case user must say what code it want to see.

> if user could enable
> it in "verbose mode". So the hint from previous point could be
> assisted by AST of offending code.

In my option we must generate fake-code if error detected in generated code
(in all case).