Even in the 'Error if grade not listed case', it was applying a small
tolerance. In the case of a fuzzy match, it was returning the inexact
grade from the import file, rather than the precise grade that Moodle
was expecting.
That causes problems when the editing form is displayed, because the
value from the database does not match any of the available options, so
the grade is changed to 0%.
Includes:
* constants refactoring
* reworked db table init
* support for $CFG->debug = -1
* functional DB tests
* fixed $DB->get_indexes() to not throw exceptions when table does not exist
* fix handling of user passwords in test db
* add debug info to exception messages
* removed unnecessary PHP debug errors from mathslib
* fixed @error suppression in get_string
* fixed PHPUnit error handler setup
* added timezone info to default install