Revert "derive show instance for Marked"

This reverts commit ffa41f524c2f3ebc2555c09716c4fe2e678f662e.
Merge branch 'master' of https://github.com/jwaldmann/haskell-tpdb
add semlab for dp
fix finite model
add cpf utility
Revert "Revert "derive show instance for Marked""

This reverts commit 86716e82a358cfb77fc026191706897fb1f7b38a.
stuff