patch 8.0.0553: toupper/tolower test fails on Mac

Problem:    Toupper/tolower test with Turkish locale fails on Mac.
Solution:   Skip the test on Mac.

patch 8.0.0552: toupper and tolower don't work properly for Turkish

Problem:    Toupper and tolower don't work properly for Turkish when 'casemap'
            is empty. (Bjorn Linse)
Solution:   Check the 'casemap' options when deciding how to upper/lower case.

patch 8.0.0551: the typeahead buffer is reallocated too often

Problem:    The typeahead buffer is reallocated too often.
Solution:   Re-use the existing buffer if possible.

patch 8.0.0550: cannot parse some etags format tags file

Problem:    Some etags format tags file use 0x01, breaking the parsing.
Solution:   Use 0x02 for TAG_SEP. (James McCoy, closes vim#1614)

patch 8.0.0549: no test for the 8g8 command

Problem:    No test for the 8g8 command.
Solution:   Add a test. (Dominique Pelle, closes vim#1615)

patch 8.0.0548: saving the redo buffer only works one time

Problem:    Saving the redo buffer only works one time, resulting in the "."
            command not working well for a function call inside another
            function call. (Ingo Karkat)
Solution:   Save the redo buffer at every user function call. (closes vim#1619)

patch 8.0.0547: extra line break in verbosefile

Problem:    Extra line break in verbosefile when using ":echomsg". (Ingo
            Karkat)
Solution:   Don't call msg_start(). (closes vim#1618)

patch 8.0.0546: swap file exists briefly when opening the command window

Problem:    Swap file exists briefly when opening the command window.
Solution:   Set the noswapfile command modifier before splitting the window.
            (James McCoy, closes vim#1620)

patch 8.0.0545: edit test may fail on some systems

Problem:    Edit test may fail on some systems.
Solution:   If creating a directory with a very long path fails, bail out.

patch 8.0.0544: cppcheck warnings

Problem:    Cppcheck warnings.
Solution:   Use temp variable. Change NUL to NULL. Swap conditions. (Dominique
            Pelle)