Support opaque cork_hash_table values

Libcork now treats `cork_hash_table` as an opaque data type.  This
patch updates the BDD code to use this new interface.
Merge branch 'feature/new-libcork-api' into develop

* feature/new-libcork-api: (22 commits)
  Support opaque cork_hash_table values
  Remove old Sphinx documentation template
  Explicit header and footer in man pages
  Don't install empty man page directories
  Fatal warnings with Intel compiler
  Build man pages based on release date
  Warnings are errors on clang
  Allow custom library installation directory
  Specify network connection to tile-monitor
  Support the Tilera platform
  Support for FreeBSD
  Fix tests/ccram to use POSIX string equality operator
  Fix add_test() to work with cmake 2.6
  Better CMake 2.6 support
  Don't use GLOB to detect library source files
  Set library version correctly
  Use cram for command-line tests
  [docs] Changed formatting for h3 and lower
  Update Sphinx configuration to work with Python 3
  Only configure @VARS in pkg-config file
  ...