Ann: SWI-Prolog 5.6.30

Hi,

I've uploaded SWI-Prolog 5.6.30.  Both new features and a bugfix release.
Below is a short summary of changes:

	Enjoy --- Jan

Prolog

  * Added function powm/3 ((B**E) mod M for large intergers)
  * Added library record (access named fields in compound terms)
  * Changed default stacks sizes from 4 MB to 32 MB
  * Various portability issues
  * Various minor issues.

Packages

  * JPL: Errornous integer check
  * PlUnit: Allow omitting list for a single test-option:
    test(name, true(X==42)) :- ...
  * Clib: Added library(sha), providing SHA-1 and SHA-256 and friends,
    including HMAC-SHA.  Fix some loose ends in recent socket rewrite.
  * HTTP: Fixed sending HTTP 302 messages.  Added final_url option to
    http_open/3 to find the final URL after redirects.  Streamline debug
    messages.
  * Semweb: Fixed two locking issues in RDF database.  Fixed two issues
    concerning rdf_reset_db.  Added MIME-type application/rdf+xml to
    rdf_http_plugin.pl.  Allow for base_uri(-URI) in rdf_load/2.
  * CHR: bugfix and maintain line-numbers.