Revert "internally use non-characters instead of PUA"

This reverts commit 8859a15446bcd34de730868399d2a81c5f75645d.

Perl < 5.14 does not like non-characters:
t/pattern-trigger.t ... Unicode character 0xfdd0 is illegal at /home/travis/build/perl-cldr/cldr-number-pm5/blib/lib/CLDR/Number/Constant.pm line 23.

See also:
https://travis-ci.org/perl-cldr/cldr-number-pm5/builds/26597857
dev v0.08_1 in readme