Minor Spring Update

In anticipation to this month's release (Caesar 58, coming on April 30th)

*** IMPROVEMENTS ***

• (Retreat) When several regions are possible, the game now selects the one that would cause the minimum amount of unit destructions (because of units that cannot follow the others or of overstacking in difficult regions).
  
• (Retreat) Attacking Sea stacks can now retreat to a port if they just get out of
  
• (Retreat) Units that cannot retreat using the locomotion type between battle region and chosen retreat region are now destroyed
  
• (Fortress Assaults) Assaulting a weakly defended fortress no longer wrongly gives combat factor bonus to the attacker and malus to the defender. It's set to zero on both sides.
  
• (Replacements) Improved realism : replacements are no longer possible for air and sea units that are not inside a structure or a transporter. It is now possible to assign replacements to units that are currently inside transport units.
  

*** FIXES ***

• (Reinforcement) Fixed bug where cards supposed to rebuild destroyed units had not effects