Bugfix, better aim cursor and small content updates

- Changed cursor to an aim mark while in-game. - Added laser aim feature (enable via settings). - Made the travel east mission in desert slightly shorter. - Fixed accidental pre-load of broken sound assets (bug you wouldn't notice but cause slower in-game loading times). - Fixed bug with stats page. - Fixed bug with broken scrollbar in empty stats page. - Fixed Revenant broken special ability. - Added artifact: Shadow Gem. - Fixed 'Axe' to enjoy fire damage bonus when reaching level 6 fire bonus. - Added weapon: 'Spike Ball'.