v0.4.0

v0.4.0 2016-11-03

Breaking changes:

• Changed the type of some low-level fields from Ctypes.ptr to
  Ctypes_helpers.Reachable_ptr.t. Those can be accessed using the setf and
  getf functions in the same module.
• Make Pkcs11_data.t abstract.

Fixes:

• Fix several use-after-free bugs (#10)

Build system:

• Add merlin configuration (#11)