MDL-20700 coding style cleanup - cvs keywords removed, closign php tag removed, trailing whitespace cleanup

and $CFG->modpixpath to $OUTPUT->mod_icon_url

MDL-12945 a slightly bigger patch for performance in recent activity and various group related issues + some other fixes - see list of subtasks in tracker; merged from MOODLE_19_STABLE

MDL-7434 all images that convey information should have alt text to convey that information - part 1

Social activities block always appears in edit mode to admin without turning editing on MDL-7639; merged from MOODLE_17_STABLE

be showed when it's null, returning false as desired.

I 'm fed up with the crappy HTML for blocks that keeps giving us
no end of trouble (bug 1718 is just the tip of the iceberg).

Rehauling things... these two divs are superfluous.

Implemented discussion from bug 2547:

* Block authors no longer need to set $this->content_type
* If you want to make a "list" block, just derive from block_list
  instead of block_base
* All switch() statements gone from library code
* Overloaded method is_empty() added to block classes for convenience

Changing the way that applicable formats for each block are defined:

The format for each page is now the same as the id attribute of the
BODY tag, which in turn is a simple function of the script's relative path:

The format for e.g. a quiz view page is "mod-quiz-view". The format for the
site index is "site-index". Exception: the format for courses is not just
"course-view", but "course-view-weeks" etc.

Obviously the applicable_formats() override for each block should now take
this into account. The matching rules now are:

* You can specify the full format, e.g. "mod-quiz-view" => true
  will allow the block to be added in quizzes
* Prefixes match the full page format, e.g. "mod" matches ALL activities
* You can use "*" as a wildcard, e.g. "mod-*-view" matches just the view.php
  page of all activities
* These rules interoperate, thus "mod-*" is the same as "mod"
* "all" remains as a catch-all situation

New naming conventions for class names to bring them in line with the
rest of Moodle. The convention for blocks is now:

class block_something extends block_base { ... }

HOWTO updated accordingly, plus some more minor polishing. More to come.

Code based on the work of Daryl Hawes for the blog module. Thanks, Daryl!

Please test the hell out of it as it's sure to have issues that need to be
ironed out.

- fixed (hopefully) all <img> tags
- global replace on <br> to <br />
- &amp; in URLs
- got the forum module XHTML compliant
Julian Sedding

Changed the way applicable formats for blocks are handled. The changes are
short codewise, but to grasp all the implications read the forum discussion
at the relevant URL.

  - display icon properly when moving items

  - display custom icons  (eg on resources)

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 :-)