Release alpha v0.8.1

In this version many things were adjusted in order to be ready for the next version which will have new buildings and maps.

[h3]Balance[/h3]

• Advanced housing buildings (downtown houses, 2-stored downtown hose and modern 2-stored house) look for density in a radius of 4, instead of 3.
  
• Wood and energy production of lumbercamps, lumberjack house/cabin and watermill increased by 50%.
  

[h3]Adjustments[/h3]

• From now on, if you unlock a skin (bike, car or truck), they will also appear in other cities.
  
• When switching to the pedestrian view, you no longer see the range boxes of the buildings.
  
• Now it is more explicit that miners' houses produce iron (ask for 5 houses instead of 1 in the tutorial).
  

[h3]Fixes[/h3]

• Music no longer stops playing
  
• Now the paths or constructions don't disappear mysteriously when building on the tree that was being cut down.
  
• When closing some windows (urbekopedia, achievements, etc) the game does not pause.
  
• Can not place [building] here -> no place to build [building].
  
• When overbuilding a road, the directions of adjacent roads are updated.
  
• Lumberjack house technicians now have the desired effect.
  
• Secondary button now no longer leaves the tooltip for building buttons flying around
  

[h3]UI[/h3]

• The initial "Choose your path" achievement screen have more information for each path: small pictures of next vehicle to unlock
  
• Before unlocking a path achievement, it shows what will be unlocked.
  
• On achieving a path achievement, a window is displayed showing the unlocked vehicle and the conditions achieved.
  
• Added colours to the effect of policies
  
• Growing trees are at the same height as everything else in the layers view.
  
• Links to building upgrades are more visible now.
  
• Now there is a tooltips to explain the 3 top right resource numbers (stockpiled, max capacity and production)