EverParse3d prelude: the F* theories for verified parser, validator
and action combinators, and the interpreter, and the partial
evaluation directives.

* EverParse3d.Prelude: combinators for parser specifications

* EverParse3d.Actions.Base: combinators for verified validators and
  actions

* EverParse3d.InputStream.Base: interface for the input stream as
  "read-and-advance"

* buffer/ : implementation of the input stream interface for
  contiguous byte arrays using Low* buffers with 32-bit lengths. The
  double-fetch proof is done via a permission system specified and
  implemented in EverParse3d.Readable and EverParse3d.InputBuffer

* extern/ : implementation of the input stream interface with bindings
  to extern C functions, whose F* prototypes are declared in
  extern/EverParse3d.InputStream.Extern.Base.fsti. This
  "implementation" is meant to link with an external C implementation
  of byte streams. See ../tests/tcpip for an example of use.

* EverParse3d.Interpreter: the 3D AST and its type, parser and
  validator interpreters, and the partial evaluation directives (F*
  normalizer rules)

* EverParse3d.ProjectorTactic: an F* tactic to generate custom
  projectors for the 3D AST
