Update of unicode_width.h to Unicode Version 7.0

Unicode Version 7.0 was released yesterday.
Run ./update_unicode.sh to update the zero_width table.
Note: the double_width is unchanged.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
refs.c: SSE2 optimizations for check_refname_component

Optimize check_refname_component using SSE2 on x86_64.

git rev-parse HEAD is a good test-case for this, since it does almost
nothing except parse refs.  For one particular repo with about 60k
refs, almost all packed, the timings are:

Look up table: 29 ms
SSE2:          23 ms

This cuts about 20% off of the runtime.

Ondřej Bílka <neleai@seznam.cz> suggested an SSE2 approach to the
substring searches, which netted a speed boost over the SSE4.2 code I
had initially written.

Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'tb/unicode-7.0-display-width' into jch

* tb/unicode-7.0-display-width:
  Update of unicode_width.h to Unicode Version 7.0
Merge branch 'dt/refs-check-refname-component-sse' into jch

* dt/refs-check-refname-component-sse:
  refs.c: SSE2 optimizations for check_refname_component