[libpng16] Bump version to 1.6.1beta07

CHANGES

diff --git a/CHANGES b/CHANGES
index 644c9e5..a00683a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4435,6 +4435,8 @@
     settings to depend on options and options can now set (or override) the
     defaults for settings.
 
+Version 1.6.1beta07 [March 4, 2013]
+
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