Correctly simplify negative type propositions in constructor

Problem

The negative type proposition constructor incorrectly simplifies
(! Any ...) to tt instead of (! Nothing ..) to ff.

Solution

Implement and/or test these optimisations:

• (is Any ..) = tt

• (is Nothing ..) = ff

• (! Any ..) = ff

• (! Nothing ..) = ff

Pull request: 46
Patch: ctyp-258.patch
Commit: 00b8d5
Release: 0.3.9