Changes throughout Moodle to remove any reserved words from the

Moodle tables.

ie user -> userid in many tables, plus in user_students
   start -> starttime and end -> endtime

I've just done all this as carefully as I could ... I don't think
I missed anything but it's pretty intensive work and I'd be fooling myself
if I didn't think I'd missed a couple.

Note that this version should pretty much be able to bootstrap itself
using PostgreSQL now ... but this is untested

mod/assignment/upload.php

@@ -59,7 +59,7 @@
                         }
                     } else {
                         $newsubmission->assignment   = $assignment->id;
-                        $newsubmission->user         = $USER->id;
+                        $newsubmission->userid       = $USER->id;
                         $newsubmission->timecreated  = time();
                         $newsubmission->timemodified = time();
                         $newsubmission->numfiles     = 1;