The exporter for mform elements does not skip "type" (which is included as a separate value).

If the plugin is using namespaces instead of frankenstyle class name,
get_called_class() will return 'type\name' instead of 'type_name'.

Added code to replace backslashes to underscores and fix that issue.

Units tests have been adjusted e.g. 'boost' instead of 'clean' in pix urls.

Some places I didn't update the test to reflect the boost markup and reset
the theme to clean. This is because the test was not testing the markup - but the
functionality (e.g. looking for specific structures to indicate an error in a form element).

If two instances of moodleforms are validated in the same run, most
likely a phpunit test run, it would store the first validation result.
Now it stores the validation result per instance, not for all instances.

Persistant input is appended for frozen elements
and should have different id then the actual element

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.

This just adds some missing types to different places
causing phpunit tests to fail.

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

Thanks Eloy Lafuente, Tim Hunt and Sam Hemelryk for valuable feedback and ideas.

Previously, we had overridden the _generateId method in almost all
subclasses; and then we mostly, but not always; ignored the value that
was generated there, and instead generated new (nicer) values in
MoodleQuickForm_Renderer::renderElement. Of course, that is not really a
logical place to (re)generate ids.

I have fixed the code so that the _generateId method now uses the 'nice
id' algorithm from renderElement. This should make the whole code flow
more logical.

This make all our overriding of _generateId unnecessary.

We do need a special _generateId for radio buttons, because you often
have different radio buttons with the same name but different values.

This change should only change the ids on radio, checkbox and
advcheckbox elements. Previously, those were essentially random, so I
don't think anyone could have been relying on the particular values.

This commit also has new unit tests, first to test the basic _generateId
algorithm, and then to create and render an example form (including some
tricky things like repeat_elements) and chech the acutal ids in the
generated HTML.

MDL-19907 rewrote validation for required fields in forms, including support for editor field. Added parameter to use strict (no spaces) required fields validation