Problem:    Sometimes VimL is used, which is confusing.
Solution:   Consistently use "Vim script". (Hirohito Higashi)

Problem:    Ubsan reports errors for integer overflow.
Solution:   Define macros for minimum and maximum values.  Select an
            expression based on the value. (Mike Williams)

Problem:    Using :change in between :function and :endfunction fails.
Solution:   Recognize :change inside a function. (ichizok, closes #1374)

Problem:    The return value of type() is difficult to use.
Solution:   Define v:t_ constants. (Ken Takata)

Problem:    Number variables are not 64 bits while they could be.
Solution:   Add the num64 feature. (Ken Takata)

Problem:    string() with repeated argument does not give a result usable by
            eval().
Solution:   Refactor echo_striong and tv2string(), moving the common part to
            echo_string_core(). (Ken Takata)

Problem:    Having type() handle a Funcref that is or isn't a partial
            differently causes problems for existing scripts.
Solution:   Make type() return the same value. (Thinca)

Problem:    No test for skipping over code that isn't evaluated.
Solution:   Add a test with code that would fail when not skipped.

Problem:    copy() and deepcopy() fail with special variables. (Nikolai
            Pavlov)
Solution:   Make it work.  Add a test.  Closes #614.

Problem:    free_tv() can't handle special variables. (Damien)
Solution:   Add the variable type.