Soldiers melee attack

[eschan145]

One thing about real battlefields is that soldiers swarm into armies and fight them with swords and spears. It is partially implemented in Armies but the fighting sucks. Many things need to be changed.

• Soldiers must not bump into other soldiers
• Soldiers should move as groups
• Soldiers have different speeds
• Soldiers use spears at close-range and swords at extreme close range
  The pymunk physics engine could help with pushing and knockback from arrows.