First Official realease of the "Blocks System".

First Official realease of the "Blocks System".
Integrated with Moodle:
    - Install automatically.
    - Update course->blockinfo for each course at installation time.
    - Modified course creation to insert into blockinfo field.
    - Modified restore to insert into blockinfo field.
    - Admin options (hide, show, delete, config) from admin page.
    - Lang strings inserted (en only).
    - Database support to mysql and postgresql (not tested!!).
Moodle, backup and block versions updated to 2004041800.
Tested with mysql: Install fresh and upgrade from previous.
section_activities block renamed to social_activities and created
its own lang file to support name "Social Activities". This can
be changed at any time.

TODO:
=====
Support it really in backup/restore.
????

Enjoy!! Ciao :-)