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: Using ":insert" in an empty buffer sets the jump mark. (Ingo
Karkat)
Solution: Don't adjust marks when replacing the empty line in an empty
buffer. (closes#892)