@hackage hybrid2.0

We have made an implementation of the language Lambda-H, described in the paper "Hybrid Type Checking" by Cormac Flanagan, which uses a hybrid type checking system. We have tried to keep our implementation as close as possible to the language defined in Flanagan's paper. The result should be seen as a proof-of-concept, and an exercise in implementing a hybrid type checker for a language with advanced type specifications.