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 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: Using the system default encoding makes tests unpredictable.
Solution: Always use utf-8 or latin1 in the new style tests. Remove setting
encoding and scriptencoding where it is not needed.
Problem: syn-cchar defined with matchadd() does not appear if there are no
other syntax definitions which matches buffer text.
Solution: Check for startcol. (Ozaki Kiichi, haya14busa, closes#757)
