Workshop

This version brings the Workshop module closer to both the original assignment module and the exercise module.

When the workshop module is used for a simple assignment (see the attached file) it now makes no reference to student assessments and their grades (there were zeros in a few of the tables). The assignment is very like the original assignment module but with fancy assessment forms and optional attachments. The assignment is in three phases/stages - Set up where the assessment form is created; Student submissions where students submit work and the teacher grades it; and Closed where the optional league table of best submissions can be displayed.

To make the module closer to the Exercise module I've added an optional password and the flagging of late submissions. Also an exercise-like workshop only has three phases (like the simple assignment workshop) as opposed to the "standard" five phases when peer assessment is involved. (There's a new internal flag which is used to switch various bits on and off depending on the "type" of the workshop being run, again see the attachment for a few more details.)

It certainly needs a bit of field testing but the module is  showing better "scaling" now. Simple assignments are beginning to look simple and the more complicated assignments switch on extra features.