This was done assuming an "indent with tab, align with spaces" approach.
get_alignment also benefited from a minor indentation fix.

get_alignment now works with columns (width), not bytes, although it is liable
to work with bytes if the given text is not a valid UTF-8 string.

remove illegal wcwidth.c include and compile wcwidth.c
fallout from irssi#480

remove illegal wcwidth.c include and compile wcwidth.c
correct #include in wcwidth.c
fallout from irssi#480

remove illegal wcwidth.c include and compile wcwidth.c
correct #include in wcwidth.c
fallout from irssi#480

remove illegal wcwidth.c include and compile wcwidth.c
correct #include in wcwidth.c
fallout from irssi#480

remove illegal wcwidth.c include and compile wcwidth.c
correct #include in wcwidth.c
fallout from irssi#480