FIX crash when no trees are present - always initialize baum_t::baum_typen_per_climate

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6325 8aca7d54-2c30-db11-9de9-000461428c89
FIX: disable all tree tools if no tree objects are available

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6326 8aca7d54-2c30-db11-9de9-000461428c89
CODE: some improvements to A*: do not try to go to parent tile, save
best new node and do not put it into queue


git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6327 8aca7d54-2c30-db11-9de9-000461428c89
FIX: when placing city attractions disable check for neighbouring special buildings if city has less than 10 buildings; code refactoring

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6328 8aca7d54-2c30-db11-9de9-000461428c89
FIX: vertical scrollbar in message window was wrong with too many messages

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6329 8aca7d54-2c30-db11-9de9-000461428c89
FIX initial size of language dialog

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6330 8aca7d54-2c30-db11-9de9-000461428c89
FIX memory leak

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6331 8aca7d54-2c30-db11-9de9-000461428c89