Problem:    Code for handling 'switchbuf' is repeated.
Solution:   Add a function to handle 'switchbuf'. (Yegappan Lakshmanan,
            closes #12397)

Problem:    Position of marker for 'smoothscroll' not computed correctly.
Solution:   Take 'list' and other options into account. (Luuk van Baal,
            closes #12393)

Problem:    Recent glibc marks sigset() as a deprecated.
Solution:   Use sigaction() in mch_signal() if possible. (Ozaki Kiichi,
            closes #12373)

Problem:    :wqall does not trigger ExitPre. (Bart Libert)
Solution:   Move preparations for :qall to a common function. (closes #12374)

Problem:    Cannot use special keys in <Cmd> mapping.
Solution:   Do allow for special keys in <Cmd> and <ScriptCmd> mappings.
            (closes #12326)

Problem:    reverse() does not work for a String.
Solution:   Implement reverse() for a String. (Yegappan Lakshmanan,
            closes #12179)

Problem:    Inserting lines when scrolling with 'smoothscroll' set.
Solution:   Adjust line height computation for w_skipcol. (Luuk van Baal,
            closes #12350)

Problem:    no functions for converting from/to UTF-16 index.
Solution:   Add UTF-16 flag to existing funtions and add strutf16len() and
            utf16idx(). (Yegappan Lakshmanan, closes #12216)

Problem:    Decrypting with libsodium may fail if the library changes.
Solution:   Add parameters used to the encrypted file header. (Christian
            Brabandt, closes #12279)

Problem:    Warnings for function declarations.
Solution:   Add argument types. (Michael Jarvis, closes #12277)