Bug fixes

• A bug was fixed where receiving an invite from a different Bytro game would trigger an exception on desktop devices and not display the invite link on mobile. 
• An issue was fixed when an enemy sea unit passing by a submarine in "Return Fire" mode would engage in naval combat and destroy the submarine, instead of the submarine remaining hidden.
• An issue was fixed that triggered an error message when switching from a mobile shop back to the game 
• A problem was solved with icons for both Fortress and Factory after Level 1. When they are put in queue the system previously suggested that the next available level is higher than the one that actually is.