various small improvements in petra (choice of units in start game, ram management and team warnings when new trade route available)

git-svn-id: http://svn.wildfiregames.com/public/ps/trunk@16054 3db68df2-c116-0410-a063-a993310a9797
Fix performance problem with unnecessary global message subscription

On my ESR31 branch, I've made two measurements with different replays (both around 15000 turns).
In the first, I got around 3% performance improvement and in the second about 7.5%. It mainly depends on how often aura changes related to the female citizen aura happen. 


git-svn-id: http://svn.wildfiregames.com/public/ps/trunk@16055 3db68df2-c116-0410-a063-a993310a9797
Merge 'remotes/trunk'