Balancing and small fixes update

Balancing changes to make the game more inviting on lowest difficulties:

• the "Forgiving" difficulty is now quite a bit more "forgiving" when it comes to money and happiness
• campaign mission have more difficulty scaling - they are slightly easier on "Reasonable" now, and much easier on "Forgiving"

Other fixes:

• Energy-driven Industry should no longer cause phantom products to remain after undo.
• Keyboard scrolling should be more pleasant now.
• You can now scroll the map using arrow keys if you prefer that/have a keyboard where WASD is uncomfortable
• The version number is now displayed in the main menu in the bottom right corner.