some fixes and cleaning in petra saved game support

git-svn-id: http://svn.wildfiregames.com/public/ps/trunk@15952 3db68df2-c116-0410-a063-a993310a9797
additional fixes for petra serialization

git-svn-id: http://svn.wildfiregames.com/public/ps/trunk@15953 3db68df2-c116-0410-a063-a993310a9797
Merge 'remotes/trunk'