support for wcs.
Support for completion semantics.
Updated documentation for weak completion semantics.
Forgot to commit this earlier.
Refactored check_tabling_options and fixed several inconsistencies in it.
addition of completion semantics as a tabling option.
reflect minor change in formatting.
Added test of intern+opaque and intern+dyn.
Made some print formats depend on compiler.
Support for writing hex/octal in write_term (forgot to commit earlier).
