compile externals now, remains to make the link between parser and
	lambda.

	local and external lambda files

	GRAMMAR updated

	GRAMMAR file added; some fixes.

of polymorphism. Lexer complete. Parser to do.

- fix one more problem with internalize
- fix variance/contravariance problem in substituterec
- cleanup

type.

This change allows sharing only for types that do not contain variables.

- performance improvements (add memoization)
- fix infinite loops due to recursive structures
- add apply tests (kim)