Checking in changes prior to tagging of version 0.20.

Changelog diff is:

diff --git a/perl/Changes b/perl/Changes
index 7910882..dc3dd5c 100644
--- a/perl/Changes
+++ b/perl/Changes
@@ -1,3 +1,7 @@
+0.20
+
+    - first production ready release with PP driver.
+
 0.16_04

     - no feature changes

perl/lib/Data/MessagePack.pm

@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use 5.008001;
 
-our $VERSION = '0.16_04';
+our $VERSION = '0.20';
 our $PreferInteger = 0;
 
 our $true  = do { bless \(my $dummy = 1), "Data::MessagePack::Boolean" };