It should be handled different how to show online submissions in new assignment module

1. Students should see their online submissions if they are not too long and not only 140 characters how it is defined in assign/submission/onlinetext/locallib.php in function view_summary. Please change it to 2000 characters for example
2. Teachers should see the students submission if it's not too long if they write feedbacks, so they can read the submission and scroll down to give feedback (same function as above)
3. in the gradingtable it's necessary to only show some characters. The gradingtable should not be that long. Therefore there should be another function shorten_text in assign/gradingtable function format_plugin_summary_with_link and it should be possible that students enter a table into an assignment. When it's only cut to 140 characters a table breaks in the gradingtable. It would be better if there is no $summary in the return