This type of assignment doesn't require anything of the student online,
it just tells them about an assignment and the teacher can provide
feedback and grades. Useful for offline activities, and also for the
teacher to add manual columns to the grades page
where data from other modules can also live later on.
Also added a README for that directory to warn teachers not to mess
with it, version code to perform the upgrade, tweaks to assignment/lib.php
and a tweak to reading module so that assignment files aren't listed
in the list of possible readings (could get messy).
If true, then display of user pictures or filenames will use the
method of providing arguments as "slash" arguments - this is much
better for caching, proxies, search engines etc. Unfortunately
it doesn't seem to work on some PHP installations.
If false (the default), then a more compatible method is used
(ie usual way of passing parameters to scripts)
