David  Dec 19 2007
    - May as well start keeping checkin notes for Bolt.
        At this point the fundamental structure of Bolt is
        more or less complete, I hope; many features are missing.

    Items for this particular checkin:

    - Make things work right when you resume a course at an
        exercise answer page.
        This creates a new View, whose prev_view_id link points
        to the exercise view, not the answer page view
    - When leave a page using "Up", terminate the view accordingly.
    - Rather than using $_GET, Form vars are now passed to exercise primitives
        in a global variable $bolt_ex_query_string, which they must parse.

    db/
        bolt_schema.sql
    html/
        inc/
            bolt_db.inc
            bolt_ex.inc
        user/
            bolt_course.php
            bolt_sched.php

David  Dec 27 2007
    - preliminary implementation of exercise_set

    inc/bolt.inc

David  Jan 1 2008
    - split control structure into separate files
    - allow passing query strings to items

    db/
        bolt_schema.sql
    html/
        inc/
            bolt.inc
            bolt_rnd.inc
            bolt_seq.inc
            bolt_xset.inc
        user/
            bolt_course_sample.php
            bolt_sched.php