CONTRIB-4124 - Remove spurious calendar event code
CONTRIB-4091 - Fix for pagination when groups or groupings used
Removed unnecessary code in the delete and add instance functions
CONTRIB-4111 - Ensure certificate dates generated use Moodle's userdate function for consistency
CONTRIB-4089 - Create a directory that is writeable so that TCPDF can create temp images
CONTRIB-4089 - Changed usage of TCPDF to PDF

The PDF class extends the TCPDF class, so the same functionality is accessible.
Fixed issue with defaults not being set when adding a new certificate
Increased version number
CONTRIB-4089 - Fixed location TCPDF folder was generated for Moodle versions 2.2 onwards
Increased version number
CONTRIB-4227 - Removed ampersands to prevent strict standards warning corrupting reports when in debugging mode
Fixed the position of the first and lastname when exporting a .txt file.
CONTRIB-4237 - Fixed the usages of the CERT_PER_PAGE and CERT_MAX_PER_PAGE
Added option to print 'grade category' grade
Removed usages of deprecated context functions
CONTRIB-4301 - Added modification protection to the default certificate types
Fixed errors in deprecatedlib.php
Check that the function exists rather than relying on the Moodle version
Fix deprecated function use in index.php.