Hotfix 0.8.10

Added a new technology “Deposits discovery” which will allow you to find new deposits of ore and clay by digging up the landscape. - Added a separate “destroy” action for some resource sources: ore veins, boulders, clay. - Fixed the generation of objects on the world map: before this fix, there was a small chance that pear forests and other resources would not be generated. The fix also affects old saves. - Fixed the display of some objects on the world map. - Fixed settlers periodically getting stuck when moving on stairs. - Fixed automatic destruction of veins when depleted. - Fixed a bug: roads built on modified terrain were displayed incorrectly.