Generate char-script-table from Unicode source. (Bug#20789)

Generate char-script-table from Unicode source.  (Bug#20789)

* admin/unidata/Makefile.in (AWK): New, set by configure.
(all): Add charscript.el.
(blocks): New variable.
(charscript.el, ${unidir}/charscript.el): New targets.
(extraclean): Also remove generated charscript.el.

* admin/unidata/blocks.awk: New script.

* admin/unidata/Blocks.txt: New data file, from unicode.org.

* lisp/international/characters.el: Load charscript.

* src/Makefile.in (charscript): New variable.
(${charscript}): New target.
(${lispintdir}/characters.elc): Depend on charscript.elc.
(temacs$(EXEEXT)): Depend on charscript.

; * admin/unidata/README: Mention Blocks.txt.

; * .gitignore: Add lisp/international/charscript.el.