Better Show, ToJSON, FromJSON instances for requests

[dfordivam]

For deeply nested requests there is a lot of overhead with ToJSON/FromJSON instances

{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Recurse","contents":{"tag":"Terminal","contents":["SomeType",[],null]}}}}}}}}}}]

Also a better Show instance will be useful in debugging