Reverted previous small buff to Volksgrenadiers (they get the cost decrease instead)

Panzergrenadiers, Volksgrenadiers and Sturmpioneers reduced in cost
MP40 accuracy slightly increased (affects Assault Grenadiers and upgraded Volksgrenadiers)
A couple additional official bug fixes implemented

Just a small buff to Volksgrenadiers

Implemented most non-balance changes from the Winter Balance Patch, and fixed a couple lingering mod bugs in the process.

Swapping Tiger for leFH 18 in Assault Support Doctrine
Why? There were 5 commanders with the Tiger I call-in and only 3 that let you build the leFH 18; now there are 4 of each. Also, it's called Assault *Support* Doctrine, not Assault Vanguard Doctrine or what have you.

Couple cost reductions. Couple bug fixes.

Field First Aid is targetable again but can be used on the casting squad
Panzerwerfer delay before firing reduced and rocket speed increased
Volksgrenadier MP40 time between bursts reduced
Schwerer Panzer Headquarters flak cannon rate of fire and reload time increased; suppression amount decreased
Rocket Barrage commander ability now correctly uses Walking Stuka rockets as its projectile

M5 and 251 half-tracks healing ability is now free to use but requires vet 2

M5 half-track gains an area heal ability
SdKfz 222 autocannon penetration reduced at longer range (to match other autocannons)
SdKfz 251 half-track gains an area heal ability
USF Vehicle Crew veterency requirements doubled
SdKfz 251/17 now displays its max range
Added a projectile to AEC Treadbreaker
Covered Trench moved from Royal Engineers to Infantry Section

Panzerwerfer rocket damage increased by 10%