Maintain composition when buying ground units.

Unit composition is defined by the doctrine. The most understaffed CP
will now get the most underrepresented unit type. Previously a random
understaffed CP would get a random unit type.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/1057.

game/settings.py

@@ -57,6 +57,8 @@ class Settings:
     perf_moving_units: bool = True
     perf_infantry: bool = True
     perf_destroyed_units: bool = True
+    front_line_procurement_target: int = 50
+    reserves_procurement_target: int = 10
 
     # Performance culling
     perf_culling: bool = False