0.15 demo update

Added: [list] [*] Tutorial level [*] Blacksmith in the village (can improve equipment for gold) [*] New artifacts [*] New melee weapons [*] Restoration and improvement of destroyed huts, road building [*] New specializations (can be purchased in rebuilt healer and shaman huts) [*] Permanent base upgrades for the blacksmith and construction [*] Achievements [*] New markers on the map, option to hide markers [/list] Minor bug fixes.