Invalid IL code on Mono

[ForNeVeR]

We have this problem on Mono, see the full log:

Unhandled Exception:
System.InvalidProgramException: Invalid IL code in Program:Main (): IL_000b: ret

I've found it while activating Travis in #22.

[ForNeVeR]

Currently reported as https://bugzilla.xamarin.com/show_bug.cgi?id=37147 but I think that we need to fix that on our side anyway.

[ForNeVeR]

I have the fix in bugfix/main-ret branch.