[nem-en] Advanced contracts handling and Mono

[Arthur Peters]

I just noticed that there is an advanced version of the contracts macros
that supports compile-time validation (in tools/contracts). That is very
cool, but I cannot use it because I am Linux only and it requires the MS
spec# code (and a few other things it seems).

Are there plans to port this to the Mono world? If so when will it
happen? If not, why not?

Also a random question about the code: Are "ensures" and "invariant"s
inherited by derived classes (aka automatically added to overriding
methods)? I would want this because it enforces the principle that
derived classes can be treated as the base class.

Happy coding.
-Arthur