Problem:    Missing support for Lua 5.4 32 bits on Unix.
Solution:   Define lua_newuserdatauv. (Kazunobu Kuriyama)

Problem:    Preferred cursor column not set in interfaces.
Solution:   Set w_set_curswant when setting the cursor. (David Hotham,
            closes #3060)

Problem:    Lua API changed, breaking the build.
Solution:   Adjust prototype of lua_rawgeti(). (Ken Takata,
            closes #3157, closes #3144)

Problem:    Static analysis errors in Lua interface. (Coverity)
Solution:   Check for NULL pointers.

Problem:    luaeval('vim.buffer().name') returns an error.
Solution:   Return an empty string. (Dominique Pelle, closes #3167)

Problem:    Lua interface does not support funcref.
Solution:   Add funcref support. (Luis Carvalho)

Problem:    W_WIDTH() is always the same.
Solution:   Expand the macro.

Problem:    FEAT_WINDOWS adds a lot of #ifdefs while it is nearly always
            enabled and only adds 7% to the binary size of the tiny build.
Solution:   Graduate FEAT_WINDOWS.

Problem:    May get ml_get error when :luado deletes lines or switches to
            another buffer. (Nikolai Pavlov, issue #1421)
Solution:   Check the buffer and line every time.

Problem:    Generated files are outdated.
Solution:   Generate the files.  Avoid errors when generating prototypes.