Simplified Chinese translation for 2.3-stable updated (#15185)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@12229 e93f8b46-1217-0410-a6f0-8f06a7374b81
code format cleanup app/models/issue.rb

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@12230 e93f8b46-1217-0410-a6f0-8f06a7374b81
code format cleanup app/models/changeset.rb

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@12231 e93f8b46-1217-0410-a6f0-8f06a7374b81
Simplified Chinese translation updated (#15186)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@12232 e93f8b46-1217-0410-a6f0-8f06a7374b81
Add support for PNG with alpha channel in pdf export (#12447)