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:    Nested function test fails on AppVeyor.
Solution:   Disable the test on Windows for now.

Problem:    When 'maxfuncdepth' is set above 200 the nesting is limited to
            200. (Brett Stahlman)
Solution:   Allow for Ex command recursion depending on 'maxfuncdepth'.

Problem:    Using freed memory with recursive function call. (Dominique Pelle)
Solution:   Make a copy of the function name.

Problem:    Marks, writefile and nested function tests are old style.
Solution:   Turn them into new style tests. (Yegappan Lakshmanan)