Add 'show/hide' hint after link for inline display

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
A couple of minor style adjustments

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
Add form validation for admin config settings

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
Use get_custom_data() method in 25_STABLE branch (deprecated in master)
Use get_url() method in 25_STABLE branch

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
Update version.php for Moodle 2.5.x release

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>