InitializeDefaultRepeatedFields() allocates memory but does not release it.
DestroyDefaultRepeatedFields is registered using OnShutdown.
Merge pull request #43 from abuszta/bugfix

Release objects allocated by InitializeDefaultRepeatedFields()
Merge remote-tracking branch 'origin/master' into 2.6.1
Update CHANGES.txt for 2.6.1rc1.
Update version number in generated files.
Update CHANGES.txt to include a bug fix.