-------------------------------------------
	Improve the "stragely-kinded tyvar" problem
	-------------------------------------------

When the type checker finds a type variable with no binding,
which means it can be instantiated with an arbitrary type, it
usually instantiates it to Void.  Eg.

	length []
===>
	length Void (Nil Void)

But in really obscure programs, the type variable might have
a kind other than *, so we need to invent a suitably-kinded type.

This commit uses
	Void for kind *
	List for kind *->*
	Tuple for kind *->...*->*

which deals with most cases.  (Previously, it only dealt with
kind *.)

In the other cases, it just makes up a TyCon with a suitable
kind.  If this gets into an interface file, anyone reading that
file won't understand it.  This is fixable (by making the client
of the interface file make up a TyCon too) but it is tiresome and
never happens, so I am leaving it.

Most of the added lines are comments.