Build 57 changelog

[pip]

Main features :
- UI that was broken after latest FAF update is fixed.
- Nomad background in game lobby
- Plenty of new sounds
- New ACU walk animation
- Other minor fixes

Balance changelog:
- T2 mobile AA : muzzle velocity = 28 (from 22), damage = 50 (from 32), rate of fire = 1.111 from 1.667, DPS = 166 (from 160)
- Heavy Destroyer : sonar range = 30 (from 20) ; AA range reduced to 30 (from 50), damage = 100 (from 50), rate of fire = 2.5 (from 3.333), AOE = 3 (from 2), muzzle velocity = 28 (from 35)
- T3 mobile artillery : cost = 960 mass (from 950), health = 1600 (from 1800), speed = 2.3 (from 2.2), deploy animation speed = 1.6 (from 1.5), turret turn speed = 35 (from 30), damage = 600 (from 620), DPS = 80 (from 82.66).