add support for constructing a DOM Tree for cues
add a fake window constructor to the test harness
oncue is only called for fully parsed nodes now, so no need to worry about the .seen flag
add a test for DOM Tree construction
add test for parsing class names in cue content
remove remaining js-shell-isms
Add missing cue-content-class.vtt.
Simple test example
Fixes to testing api
Refactor runTest
Test vertical cuesettings by comparing to JSON.

I've also separated the vertical cue setting tests out into their own
vtt files and hooked them into their own JS test runner.
Introduce new test harness that reads from test.list files.

- Test harness now recursively reads through directories with test.list files
in them and executes tests based on the information contained within.
- Test.list files currently can contiain further includes of test.list files
in subdirectories or information for tests that can compare the parsed vtt
file to data in a JSON file or, alternatively, can use custom assertions contained
within a js file.
Update README to describe how to make tests.
Move cue setting align tests over to new test harness.
Reorder vertical/test.list to be in alphabetic order.