The code switched meanwhile to use :x1, :x2, :y1, :y2 over :coords as
parameters.

Use File.expand_path() everywhere so as to be able to run one test file
with:

$ ruby path/to/test_file.rb

A couple of test errors were thrown and an exception showed up when the
"Grades" tab was selected for a marks spreadsheet. As it turnes out, the
problem was that the lambda took no arguments but was called with two
arguments. See app/controllers/grade_entry_forms_controller.rb
line 29. This fix only changes the offending lambda to take two dummy
arguments. That is needed as the pagination helper routine is also
called by the submissions table controllers.

Fix remaining test failures