The previous method of generating the id attribute of the elements
within the modgrade group did not take the name of the modgrade field
into account. So if there were multiple fields of the modgrade type
added into a form (not a common case yet still valid), elements created
within the group were assigned same id attributes.
The patch introduces a new method for generating the id attribute of
modgrade elements. The new method takes the name of the modgrade group
into account and returns the id in the format similar to the default one
returned by HTML_QuickForm_element::_generateId().
The patch changes the generated id attribute. Apart from the
block_activity_results' behat feature files, not other places seem to
rely on the exact value.
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
