Improved community maps support + leaderboards

Steam workshop integration improved
Community maps now also show recent workshop items, not only subscribed ones
Main menu now displays a box with options to start endgame modes + shows 3 newest community maps
Implemented leaderboards for community maps
Selected archive of map creator is published together with map, so everyone can play with the original archive entry of the creator, making leadboards and best times more meaningful
Improved overall GUI of community maps, now also displaying the map name set in steam workshop
integrated steam workshop voting system

Other

Fixed bug where published community maps where hidden in the workshop by default
Warning in map editor when trying to save map without preview image
Fixed bug in editor where info text would overdraw other text
map editor now automatically assigns kill-all goal when adding first enemy and removes the goal once all enemies deleted.
Daily random time trial for now offline.
minor improvements