Add a number of abbrs and variants to \N{}

This patch adds the standard abbreviations for the control characters
(such as ACK, BEL, etc) to the repertoire that \N{} knows about.  It
also adds a few common variants of their full names, and the old names
for the 4 controls that Unicode has chosen not to have any names at all
for.

The patch also adds all the abbreviations that Unicode lists in 5.2 for
longer characters, such as NBSP, SHY, LRE, ...

To preserve complete backward compatibilty for these and future changes,
user-defined aliases are now checked first, before these are.

As a performance enhancement, these aliases are mapped to their actual
code values instead of their full names which then had to be looked up
in the large table.  Now that is avoided, and the table is not loaded
at all until a name is encountered that is not one of these aliases.

The pod and .t are updated.

1 files changed, 11 insertions, 0 deletions

diff --git a/pod/perl5133delta.pod b/pod/perl5133delta.pod
index 1cf19d87d8..f16dcf9e48 100644
--- a/pod/perl5133delta.pod
+++ b/pod/perl5133delta.pod
@@ -28,6 +28,17 @@ here, but most should go in the L</Performance Enhancements> section.
 
 [ List each enhancement as a =head2 entry ]
 
+=head2 C<\N{I<name>}> understands a a number of new abbreviations and names
+
+C<\N{}> now knows about the abbreviated character names listed by Unicode, such
+as NBSP, SHY, LRO, ZWJ, etc., as well as all the customary abbreviations for
+the C0 and C1 control characters (such as ACK, BEL, CAN, etc.), as well as a
+few new variants in common usage of some C1 full names.  A complete list is in
+L<charnames>.
+
+In the past, it was ineffective to override one of Perl's abbreviations with
+your own custom alias.  Now it works.
+
 =head1 Security
 
 XXX Any security-related notices go here.  In particular, any security