Print intermediate type checking state in verbose mode

Clarification and motivation

tezos-client typecheck script prints every intermediate type signature if you pass -v flag to it. It is very convenient, especially if you write your own contract, it turns out to be ill-typed and you need to debug it. It would be good to implement such behavior in our typecheck as well.

Acceptance criteria

morley typecheck should print every intermediate type signature if verbose flag is True (regardless of whether the contract is well-typed or not).