Problem:    MS-Windows: most users expect using Unicode.
Solution:   Default 'encoding' to utf-8 on MS-Windows. (Ken Takata,
            closes #3907)

Problem:    QuitPre is triggered before :wq writes the file, which is
            different from other commands.
Solution:   Trigger QuitPre after writing the file. (closes #8279)

Problem:    Not enough tests for writing buffers.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes #8229)

Problem:    Get readonly error for device that can't be written to.
Solution:   Check for being able to write first. (closes #8205)

Problem:    Bufwrite not sufficiently tested.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes #8192)

Problem:    Some tests fail when run as root.
Solution:   Use CheckNotRoot.

Problem:    Tests fail when run as root.
Solution:   Add a comment mentioning the expected failure. (issue #7919)

Problem:    Write file test still fails on MS-Windows.
Solution:   Set fileformat with the :edit command

Problem:    Write file test fails on MS-Windows.
Solution:   Force edit after setting 'fileformat'.

Problem:    First write after setting 'eol' does not have NL added. (Tomáš
            Janoušek)
Solution:   Only use b_no_eol_lnum when doing a binary write. (closes #7535)