Problem: Various inconsistencies in test files.
Solution: Add modelines where they were missing. Use Check commands instead
of silently skipping over tests. Adjust indents and comments.
(Ken Takata, closes#6695)
Problem: Not all windows commands are tested.
Solution: Add more tests for windows commands. (Dominique Pelle,
closes#1575) Run test_autocmd separately, it interferes with
other tests. Fix tests that depended on side effects.
Problem: Vim can create a directory but not delete it.
Solution: Add an argument to delete() to make it possible to delete a
directory, also recursively.
