ADVENT OFFICER - Call for reinforcements

Gives Advent Captains the ability to summon reinforcements to help them enter the battlefield!

This ability can only be used once, and will only be used by the AI ​​when he sees that you have eliminated all of his companions (against multiple enemies alone). Hopefully this will make a unit that wasn't previously pumped more dangerous, change player targeting priorities, and expand the concept of enemy units that might already be more numerous.

This skill uses an action point, allowing the captain to move again when called, or to move to better coverage before being called. Reinforcements are always in the alien ranks and adapt to the player's power level as usual (meaning harder enemies further into the game).

If I accidentally break something of yours, please feel free to provide feedback, help with improvements, and scream at me.

*****Using the UIScreenListener class - obviously breaking the tutorial*****

*****Edit Advent Captain template and its AI behavior tree*****

Changing the template can be very temperamental. I've done it now, so it adds the ability to the strategy screen, which means loading combat directly into combat *is* possible without it - working on that.

ToDo：

• Find out the positioning method/style and use a more appropriate method
• Find out how to add Advent chatter to your animations
• Possibly get CineScript to work for it
• Changed ability icon from evac to custom
• [strike] Possible change to XCom's ideal Spawn distance, based on feedback[/strike]

ChangeLog 19/02/16：

• Added .ini files to cusstimisation the types of reinforcements being called, and the distance at which it will attempt to call them.
• Descriptive comments on how to change reinforcements and create custom sets
• No longer spawns in the center of Xcom Squad, but in random directions and the number of tiles you set.
• The default distance is 50 square meters, but no matter what value you set, the game will always spawn within line of sight