Library for regular data types

Provides functors and typeclasses implementing functionality expected for a regular data type, like i/o, containers, printing, etc.

In particular, the library includes:

• module Data that adds generic i/o routines for each regular data type.
• module Cache that adds caching service for data types
• module Regular that glues everything together
• module Opaque for regular but opaque data types
• module Seq that extends Core_kernel's sequence module
• module Bytes that provides a rich core-like interface for Bytes data type.