- 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)

to the main suite, R and SEQ to the extended suite.

has not been built, only displaying a warning.

committing. To install the hooks locally: tools/install_hooks.sh

Add tests on polymorphism (not supported) in the extended suite.