Russian Heavy Machinegun Mod

[Mobius]

This mod adds the Russian DShK-39 Heavy Machinegun to the Russian inventory.
It renames the Maxim 7.62mm as a MMG.
It also changes the penetration values of the early 12.7mm AT rifle.

One problem I did find while making the mod is that there is a Russian infantry unit called "Anti-Tank Rifle" that is listed as having a PTRD-41
in 1939 to 1942. This is incorrect since it is before that guns time. No PCK scenario uses it in 1941 but it might show up in a
random campaign or battle for that year so should be eliminated.