Problem:    Various small problems in source files.
Solution:   Fix the problems.

Problem:    Older GTK versions don't have gtk_entry_get_text_length().
Solution:   Add a function with #ifdefs to take care of GTK version
            differences. (Kazunobu Kuriyama, closes #2605)

Problem:    GTK: :promtfind does not put focus on text input. (Adam Novak)
Solution:   When re-opening the dialog put focus on the text input. (Kazunobu
            Kuriyama, closes #2563)

Problem:    W_WINCOL() 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:    Crash when using some version of GTK 3.
Solution:   Add #ifdefs around incrementing the menu index. (Kazunobu
            Kuriyama)

Problem:    Some macros are in lower case.
Solution:   Make a few more macros upper case.

Problem:    Some macros are in lower case.
Solution:   Make a few more macros upper case. Avoid lower case macros use an
            argument twice.

Problem:    Build error on Fedora 23 with small features and gnome2.
Solution:   Undefine ngettext(). (Hirohito Higashi)

Problem:    Various problems with GTK 3.22.2.
Solution:   Fix the problems, add #ifdefs. (Kazunobu Kuriyama)