Improved def file usability

[Goosius1]

• With current code, it seems difficult to configure the def files so that they don't fail, never mind getting the required result in terms of province appearance.
• This PR improves the usability of def file
• With this they should be fairly bulletproof for actually working, and also easier to use for designing.
• Now they look like this:

  top_left_corner_location: -2434,-2049
  bottom_right_corner_location: 4064,2056
  average_province_size: 50000
  brush_square_radius_as_percentage_of_province_square_radius: 60
  brush_max_move_as_percentage_of_province_square_radius: 40
  brush_min_move_as_percentage_of_province_square_radius: 20
  max_brush_moves: 100
  new_town_cost: 250
  upkeep_town_cost: 10