Add a checkbox for auto-scrolling in the test runner

Sometimes, it can be useful to be able to inspect previous test results
while tests are still running. Add the option to disable auto-scrolling
the test list in the test runner for this purpose.

The patch is made to 1.0.2 and later versions of the suite, where the
test runner is identical.
Merge pull request #393 from NVIDIA/autoscroll-checkbox

Add a checkbox for auto-scrolling in the test runner