The case of lam and case expressions that before required the terms to be
well-typed now require terms to be closed.

Separated definition context and context refinement from soundness_binary file.

Squashed commit of the following:

commit a8d2dd620df2fe8531b590811b7f08d2bc1289b4
Author: Amin Timany <amintimany@gmail.com>
Date:   Sun May 29 13:54:07 2016 +0200

    Prove refinement of fine/coarse-grained stack

commit 6347ef920581b4f21b5dfa74d288afcf482c9b50
Author: Amin Timany <amintimany@gmail.com>
Date:   Sun May 29 01:37:23 2016 +0200

    Backup

commit 39552d8055f55458c9515e629707d496e26e92b7
Author: Amin Timany <amintimany@gmail.com>
Date:   Sat May 28 22:40:02 2016 +0200

    Backup

This is to avoid confusion when Coq loads the module.

It now produces a lambda that when evaluated with a value runs the underlying
lambda that value after acquiring the lock. As before, the lock is released
afterwards.

It now returns the value of the expression evaluated.