Reapplies and revamps functionality on the assignment table.

* Reapplied the table data changes to also change to the mycourse object.
* Added in error checking for table changes.
* Added so the user can see Ghost Names (the psuedoname) of the students.
* Added tab functionality that Shade was wanting (Enter key will need to be looked at).
* Made it also so when using tab or enter actually makes the cell that the user is about to edit more focused.