A bugfix patch

A patch which fixes some bugs that came with the recent necropolis update, aswell as some older ones: [list] [*]The new necropolis achievements are now unlocked properly. [*]Idle skeleton workers are now properly displayed as idle workers. [*]Builders will no longer try to reach wall sections which are within mountains or other non-reachable places. [*]Pine trees in forest environment now appear as normal trees again, rather than in their death-influenced shape [*]The flying behaviour of falconer - hawks around obstacles has been improved. Among other things they will now fly over mountains rather than through them. [/list]