[nem-en] recent change in the typer

[Michal Moskal]

Hi,

I've just (r6968) change to the typer, so it allows intersection
types. They were there since the very beginning (of NTE at least), but
were not used very much. The idea behind intersection type (T1 and T2)
is the set of values that poss both T1 and T2 types (so it makes most
sense for interfaces).

Anyway if you encounter strange bugs/compiler messages with types with
"AND" inside them, please report.

-- 
   Michał