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:    Some mapping code is not fully tested.
Solution:   Add more test cases. (Yegappan Lakshmanan, closes #5519)

Problem:    Some balloon tests don't run when they can.
Solution:   Split GUI balloon tests off into a separate file. (Ozaki Kiichi,
            closes #4538)  Change the feature check into a command for
            consistency.

Problem:    Tests are silently skipped.
Solution:   Throw an exception for skipped tests in more places.

Problem:    Langmap test fails with normal build.
Solution:   Check for +langmap feature.

Problem:    'langmap' applies to the first character typed in Select mode.
            (David Watson)
Solution:   Check for SELECTMODE. (Christian Brabandt, closes #572)
            Add the 'x' flag to feedkeys().