Merge branch 'bb/unicode-9.0' into maint

The character width table has been updated to match Unicode 9.0 * bb/unicode-9.0: unicode_width.h: update the width tables to Unicode 9.0 update_unicode.sh: remove the plane filter update_unicode.sh: automatically download newer definition files update_unicode.sh: pin the uniset repo to a known good commit update_unicode.sh: remove an unnecessary subshell level update_unicode.sh: move it into contrib/update-unicode