Previously, ELinks used to silently discard the Alt modifier from
Alt-ö keystrokes when UTF-8 I/O was enabled. Now, separate actions
can be bound to ö and Alt-ö.
However, if CONFIG_UTF_8 is defined, then actions cannot be bound to
non-ASCII characters, regardless of modifiers. This is because the
code that handles names of keystrokes assumes a character can only be
a single byte. This commit does not change that.