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/choice/index.php

@@ -28,7 +28,7 @@
         notice("There are no choices", "../../course/view.php?id=$course->id");
     }
 
-    if ( $allanswers = get_records("choice_answers", "user", $USER->id)) {
+    if ( $allanswers = get_records("choice_answers", "userid", $USER->id)) {
         foreach ($allanswers as $aa) {
             $answers[$aa->choice] = $aa;
         }