Problem:    "%v" in 'errorformat' does handle multi-byte characters.
Solution:   Handle multi-byte characters. (Yegappan Lakshmanan, closes #3700)

Problem:    Still using FEAT_VIRTUALEDIT.
Solution:   Remove last use of FEAT_VIRTUALEDIT.

Problem:    Too many #ifdefs.
Solution:   Graduate FEAT_MBYTE, part 3.

Problem:    Argument for message functions is inconsistent.
Solution:   Make first argument to msg() "char *".

Problem:    printf format not checked for semsg().
Solution:   Add GNUC attribute and fix reported problems. (Dominique Pelle,
            closes #3805)

Problem:    Giving error messages is not flexible.
Solution:   Add semsg().  Change argument from "char_u *" to "char *", also
            for msg() and get rid of most MSG macros. (Ozaki Kiichi, closes
            #3302)  Also make emsg() accept a "char *" argument.  Get rid of
            an enormous number of type casts.

Problem:    Cannot easily change the current quickfx list index.
Solution:   Add the "idx" argument to setqflist(). (Yegappan Lakshmanan,
            closes #3701)

Problem:    Adding quickfix items marks items as valid errors. (Daniel Hahler)
Solution:   Check when items are valid. (Yegappan Lakshmanan, closes #3683,
            closes #3633)

Problem:    Using illogical name for get_dict_number()/get_dict_string().
Solution:   Rename to start with dict_.

Problem:    Cannot distinguish between quickfix and location list.
Solution:   Add an explicit type variable. (Yegappan Lakshmanan)