This 'report' is actually a tool that lets you edit all the dates for all the activities in your course on a single page.
This question type was created by the Open University (http://www.open.ac.uk/).
Once the plugin is installed, you can access the functionality by going to Reports -> Dates in the Course administration block.
Install from the Moodle plugins database
Or you can install using git. Type this commands in the root of your Moodle install
git clone https://github.com/moodleou/moodle-report_editdates.git report/editdates
echo '/report/editdates/' >> .git/info/exclude
Then run the moodle update process Site administration > Notifications
This plugin needs to know about what dates are contained in each activity or block. This is done by code in separate classes. For some things, these classes are in this plugin: https://github.com/moodleou/moodle-report_editdates/tree/master/mod, https://github.com/moodleou/moodle-report_editdates/tree/master/blocks.
For other plugins, there is the option to put the class in the other plugin.
You need to make a class called mod_mymodname_report_editdates_integration,
which therefore goes in mod/mymodname/classes/report_editdates_integration.php.
For blocks, the equivalent class is block_myblock_report_editdates_integration.