[nem-en] Debug support

[vc]

> This would be a major slowdown, because we translate all loops into
> local functions, which are then automatically inlined by compiler. So
> every 'foreach,for,while' would be changed into separate method, all
> local variables used by them would need to be stored in closures, etc.
> Also... as every loop would be treated as "skippable" function, you
> would get strange behavior stepping over them - the debugger would
> skip entire loop execution if you clicked "step over".

Oh... :)

> But in general I don't think there is something, which would make it
> impossible.

It will be necessary investigate debugger API. May be it help to solve a
problem.